@Mio: My guess is that either like Sereg said, she was helpless when she first got there and needed his support, or otherwise she decided that since he appears to be a reasonably popular guy she figured that getting in good with him would be a good way to boost her own position. By the time he realized that she didn't really care about him much, she was already at the top of the food chain.
@Kegisak: I see what you mean about Flash, but I still think he's flat compared to Sombra for 2 reasons:
1. Sombra was a story-relevant character. Even though we didn't see much of him, his existence was integral to the story, whereas Flash you could remove and not much would change.
2. We were actually informed in the story about Sombra's abilities and personality, if only indirectly. We didn't see
him much, but we knew that the events were due to his preparations, which in turn revealed his personality. Flash didn't have that; he didn't do anything that another character couldn't have done (finding the photos was more a case of "the new girl doesn't look like she'd do that, and SS is enough of a bitch to fake it...", and there are any number of characters who could have connected those dots). The only thing that really makes him unique is that he's SS's ex, and the story basically never mentions that again.
@Meta: That was actually one thing I appreciated about him. They took a douchetastic character type (guitar-playing Fonzie wannabe) and made him okay. Only problem is he didn't get developed as much as RD or Rarity and resides firmly in Generic Nice Guy territory.
edited 8th Jul '13 12:36:26 PM by JapaneseTeeth