Who do you think it really is?

Spike

I heard it's Megan especially because of how she can touch this pony in a way no other Equestrian creature could.

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touch this pony in a way no other Equestrian creature could.

Wait a second...
Are you telling me that...

You're right! Megan's right hand isn't seen which means it must be parallel to Twilight.
And the way Twilight is looking back and the face she's making...
Megan really is touching Twilight where the sun never shines. You're absolutely right!
And it makes perfect sense since she has fingers. I don't think a hoof would fit in there.

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For some reason, Twilight is actually alright with Megan grabbing her butt as is Spike.

7922707 Oh, Megan...

Now we know why she likes to be a farm girl, surrounded by all the animals. Furries have nothing on Megan; she's the real deal.

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If you were to watch the actual ending of Escape from Catrina, you would see Megan actually kissing Sundance on the lips.

7923092 Intimacy is magic!

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Megan also goes on record for booping a pony on the snout as she did that to Sweet Stuff in the original MLP movie after singing There's Always Another Rainbow.