(Picture of the OC is in the story's thumbnail)
"Twilight!"
"Coleus!"
Rainbow watched as Twilight lunged forward, wrapping her hooves around some strange stallion. Rainbow made her way to the castle doorway and looked outside. In her marefriend's hooves was a unicorn with a blue coat, purple straight hair, and a lighter shade of purple for his eyes. Twilight mentioned that an old friend was gonna be visiting today, which was strange to Rainbow since she thought Twilight didn't really have friends in Canterlot.
Rainbow took a moment to consider who this guy could be. "Maybe a tutor, somepony from the library, an actual friend... or... maybe a coltfriend... I'm pretty sure Twi can go both ways... as Rainbow wrapped up her possible conspiracies she decided she'd just find out for herself. As she left her thoughts and came back to reality, she saw that they were still hugging.
"Ahem!"
Twilight quickly broke away from the hug and turned around towards an annoyed Rainbow Dash.
"Oh! Sorry Rainbow you haven't met. This is an old friend of mine from Canterlot, his name's-"
"Coleus" the stallion answered for her. Twilight smiled at him over her shoulder and he returned the gesture.
"Coleus? What kinda name is that?" Rainbow asked much to the irritation of Twilight. It was rude way to go about asking that.
"It's the name of a flower"
"Pfft! A flower, really? You're named after a flower" Rainbow started to chuckle but was silenced by Twilight glaring at her.
"Let me remind you that your first name is Rainbow" she deadpanned, causing her to grin sheepishly.
"Yeah.. fair enough. Well my name's Rainbow Dash aaaaannnddd" she stretched the word as she grabbed Twilight around the shoulders to bring her by her side. "I'm this babe's marefriend" Rainbow boasted, only serving to annoy Twilight more.
"Well it's nice to meet you. I'm glad to see Twi here was able to make some more friends after she left Canterlot, I always knew you had it in you" Coleus said as he leaned in to nuzzle Twilight real quick. Rainbow glared at the two, practically fuming.
"Is he really nuzzling her!? and he even called her "Twi"... I CALL HER TWI! Rainbow thought, some of it almost slipping out of her mouth.
"I thought you didn't really make any actual friends in Canterlot, Twi" she emphasized her marefriend's nickname.
"Well technically it wasn't in Canterlot it was on a trip. It was a few years back when Celestia wanted me to get out of the stuffy library and go explore and see things for myself. She sent me on a research trip to the San Palomino Desert to look at old artifacts, and Coleus was an archeologist there. It was only a few weeks, but since we both shared an interest in ancient history... we sort of clicked. I was naive back then and didn't really care as much about friends, you know that, so after a few weeks I just went home and that was that. I only recently just thought back on it all and how nice it was since I have a better perspective on it now" Twilight explained, and Rainbow listened intently for any mentioning of a coltfriend.
"Coleus did always mention things about friendship, but of course I only shrugged it off back then" Twilight finished as she smiled towards Coleus.
"I told him to come meet me here in Ponyville though to see what changed and how i've made friends with you and the girls, and well.. fell in love with you" Twilight said as she beamed towards Rainbow but quickly turned back to Coleus.
"I'm sorry I never listened to you back then. You'd always try to talk about love and feelings but I was so close minded back then" Twilight said as Rainbow raised a skeptical eyebrow.
"Love and feelings?"
"It's no problem Twilight, honestly. I'm just happy to see that things turned out well for you, I mean hay you're a princess now!" he complimented, causing Twilight to blush.
"Yes well, from what you said in your letter you've risen to be quite the archeologist. You've discovered three entirely new types of prehistoric creatures, not many in your field can say that. Oh and you look really handsome now too, you were a lot more thin back then" Twilight teased as she raised Coleus' hoof to examine it. Rainbow glared, noticing Coleus flexing.
"Yeah well i've been working out lately, forty pull ups a day at the least. It's hard cause of how hot it is out there, but I can handle it" he said with a laugh while flexing his hooves. Twilight bumped him on the arm.
"I'm serious though, you really look like you're doing well for yourself"
"Yeah well, who cares what boring stuff i've been up to. You've definitely had the more exciting life so far, and I'd love to meet your friends as well as get to know your marefriend better" he said as he nodded towards Rainbow, who's glare switched into a smile as he looked her way, and then back to a scowl when he looked towards Twilight.
Rainbow could have sword she had seen Twilight's eyes... wandering.. on that guy a bit too much. He was definitely in good shape... too good of shape. Strong bulky muscles could make any mare swoon, Rainbow had her eyes on him.
Twilight took Coleus' hoof and led him inside the castle, Rainbow hesitated to follow and noticed Lyra and Bon Bon walking by.
"Wow Twilight looks pretty cute with that hunk she dragged inside" Lyra muttered. Rainbow stared daggers at the two, even growling while she did. The two mares picked up the pace and bolted around behind a house to avoid Rainbow's rage.
_____________________________________________________________
The three of them had sat down in Twilight's sort of living room of the castle. Twilight and Coleus on the couch, and Rainbow on a recliner staring at them.
Twilight had started off by talking about the girls and some of the adventures they had. Coleus nodded along with every juicy detail of their Equestria saving tales. The topics switched onto Rainbow as Coleus asked all about her, and Rainbow "happily" answered each question through gritted teeth. It went on about the Wonderbolts, the Rainboom, and then about how her and Twilight became a thing.
"Wow, a stuntpony getting with a princess, never thought i'd see the day" Coleus chuckled, and Twilight laughed along with him. Rainbow scowled at the two.
"Oh so cause i'm a stuntpony i'm not good enough to date a princess? Rainbow was furious, but silently furious.
At one point Coleus stepped outside and came back in with a saddle bag. He decided to show off some cool nicknacks from the area and he had photographs from some traveling he had done before Ponyville. Rainbow leaned over to peek at the photos, noticing something very odd about all of them. In every picture he would be in a whole new place... but with a whole new mare in his arms. Each photo was pretty much the same thing, some cool scenic place and then him standing there with a hoof slung over a different mare's back in each picture.
After little bit more of discussion Rainbow asked to speak to Twilight outside. Rainbow and Twilight stepped out into the hall, the latter being confused.
"Twilight, what is going on in there?"
"What do you mean?"
"He's totally got a thing for you"
'What? No, what makes you say that?"
"He nuzzled you"
"So what we nuzzled when we were just friends, and I still nuzzle our other friends"
"You hugged"
"I hug our other-"
"for a REALLY long time"
'Well... it was sort of long but still-"
"He didn't hesitate to flex his muscles"
"He was joking"
"I doubt it, and plus that stuntpony comment. He doesn't think i'm good enough for you"
"It was just an observation. You have to admit it was pretty crazy that a Wonderbolt's trainee is together with a princess right?"
"Oh.. so you don't think i'm good enough either..." Rainbow said, her tone sounding sad.
"What? No, that's not what I mean. I'm sorry Rainbow it's not like that it's just-"
"No.. no I get it I get it. It is a little weird I guess" Rainbow said as Twilight sighed.
"Good because I don't want you thinking that. Your social status doesn't have any effect that could keep me from loving you"
"Well good cause I hope this next argument point doesn't make you hate me"
"Rainbow!"
"He had pictures of several different locations and EACH one had a different mare in his hooves. Come on Twi, he totally gets around"
"Rainbow! Would you stop it! I love you and I already told you that, honestly I just think you're jealous"
"Me? jealous!?"
"Yes, and it's immature Rainbow. Don't act like you haven't been glaring at him all day so far, and yes i've noticed. You've been fuming to yourself every time you look at him and I want it to stop Rainbow. It's also not fair for you to judge him so quickly, you don't even know him. You've known me forever now which means I expect for you to KNOW that I won't cheat on you, not ever. Okay Rainbow?" Twilight asked, with both a hint of sincerity but seriousness.
"Fine" Rainbow grumbled, and the two went back in. As they neared him on the couch Twilight took notice of his empty cup.
"Oh are we out of tea? Here let me go get some more" Twilight said as she levitated the tea kennel with her magic and turned to leave the room. Rainbow and Coleus were the only ponies remaining in the room, the latter getting up from the sofa and trotting over to her. He didn't hesitate to step right up to her and shove his face directly in-front of hers.
"I'm serious you know" Coleus said, unusually serious.
"Uh.. what?"
"I'm serious about what I said, you're not good enough for her.. but I am. Give it a few days and i'll have her wrapped around my hoof, and then while i'm in bed with her having a good time, she'll have already kicked your loser flank out on the street. You try and get in the way of all that, then we're gonna have a problem" Coleus said with a sadistic grin. His eyes seemed to stare deep down into her own, looking for any sign of trouble.
Rainbow just stared at him, now with a slack jaw as he threatened her relationship. As she tried to recollect her thoughts on what he'd just said Twilight was already back with the tea.
"Oooh looks good" Coleus smiled as he went back to the couch and waited for his tea. Twilight smiled towards him as she set the tea down but grimaced towards Rainbow. She leaned in and gave a quick peck on the pegasus' cheek, but she didn't respond.
"Um.. are you alright Rainbow?"
She simply stared at Coleus, as he grinned at her from behind Twilight's back.