Ada is good girl. Thought it's questionable that she is working for Wesker, she has her own goals and motives. Besides, these stories are somewhat predictable. Leon, the RE favorite of the fans, and a major protagonist is in love with her. The hero always gets the girl. At the very least, there is a bitter sweet ending in which she shows her good side and saves him or something, then dies. Kind of like how RE2 was thought to have ended on Leon B. Another possible direction for the story to go is for Ada to cross him, and feeling hurt and distraught, gets his spirits lifted by a different female protagonist who helps him take her down and then go live happily ever after. Every story tends to follow these certain clechades. So,yeah. My guess is, she's a good girl.