Let's see. From what I remember about these situations it's usually like so. (This is from my experience. I'm sure others would say differently.).
Applejack or Rainbow Dash falling for a human.
Twilight's the most used when it comes to crossover shipping.
Fluttershy, Rarity, and Pinkie aren't used as much with humans or crossover stuff. So they might be better if you're going for originality.
But personality wise, I'd say this also.
Rainbow Dash is too abrasive. Unless this is going the hate/hate until they fall for each other (not a fav thing for me) I don't think it's going to work.
Twilight....No. They personality clash too much. He's an aggressive soldier and she's bookworm. (Yes, she has a brother she looks up to who is a soldier, but Capelli isn't much like her brother.)
Applejack remind me a tad of Susan. (The blond hair helps.) Minus the southern accent of hers, they are very similar. They are extremely loyal and care for their family. (Yes she ratted out Hale, but she was looking out for her fellows. She did keep him safe and allowed him to go though.) Both stubborn and ground to their own ideals. Also, both can hold their own and dish out some. So that might work.
Fluttershy could be an interesting pick. She's weak and almost helpless while he's strong and abrasive. (By Resistance 3 he's worked past that and is a likable kind of person.) She could help ease him to be a better person and he could protect her.
Rarity...Would actually be interesting if not strange. I really have no idea how it could be done, but if done right, it would be smashing.
Of course that's just the main six. If others are available, I'll lend my thoughts and try to help.
{Note} He doesn't need to learn loyalty really. He was loyal to the cause and only mistrusted Hale because he was going to turn...Yes he was a real jerk, but again, Resistance 3 proves he can change. (And he makes and excellent husband/father....Might be interesting to see if you consider a sequel.)
I almost forgot Pinkie. Again, not sure if this one would work. She's super energetic and loves to be around people. It would take a long time for him to be comfortable to such things.
Also it's nice too see more Resistance crossovers. I know I was the first and it was so annoying when I had to explain what I was crossing over.
(On a side note, would it be possible if I could get your assistance? I"m trying to go back and rework my story so I can finish it.)
I would have made his mark the [url=data:image/jpeg;base64,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]symbol from Retribution
pinkie pie
Fuck it, go Fluttershy! I have yet to read a fan fiction with her in a relationship in this form/way/type of person.
Why don't you just have Capelli be paired with Derpy? I think she needs somepony to love her.
Let's see. From what I remember about these situations it's usually like so. (This is from my experience. I'm sure others would say differently.).
Applejack or Rainbow Dash falling for a human.
Twilight's the most used when it comes to crossover shipping.
Fluttershy, Rarity, and Pinkie aren't used as much with humans or crossover stuff. So they might be better if you're going for originality.
But personality wise, I'd say this also.
Rainbow Dash is too abrasive. Unless this is going the hate/hate until they fall for each other (not a fav thing for me) I don't think it's going to work.
Twilight....No. They personality clash too much. He's an aggressive soldier and she's bookworm. (Yes, she has a brother she looks up to who is a soldier, but Capelli isn't much like her brother.)
Applejack remind me a tad of Susan. (The blond hair helps.) Minus the southern accent of hers, they are very similar. They are extremely loyal and care for their family. (Yes she ratted out Hale, but she was looking out for her fellows. She did keep him safe and allowed him to go though.) Both stubborn and ground to their own ideals. Also, both can hold their own and dish out some. So that might work.
Fluttershy could be an interesting pick. She's weak and almost helpless while he's strong and abrasive. (By Resistance 3 he's worked past that and is a likable kind of person.) She could help ease him to be a better person and he could protect her.
Rarity...Would actually be interesting if not strange. I really have no idea how it could be done, but if done right, it would be smashing.
Of course that's just the main six. If others are available, I'll lend my thoughts and try to help.
{Note}
He doesn't need to learn loyalty really. He was loyal to the cause and only mistrusted Hale because he was going to turn...Yes he was a real jerk, but again, Resistance 3 proves he can change. (And he makes and excellent husband/father....Might be interesting to see if you consider a sequel.)
I almost forgot Pinkie. Again, not sure if this one would work. She's super energetic and loves to be around people. It would take a long time for him to be comfortable to such things.
Also it's nice too see more Resistance crossovers. I know I was the first and it was so annoying when I had to explain what I was crossing over.
(On a side note, would it be possible if I could get your assistance? I"m trying to go back and rework my story so I can finish it.)
I would have made his mark the [url=data:image/jpeg;base64,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]symbol from Retribution