Secret Identity. Identity Trilogy, #1

Brenda McKay has no man in her life, and she really doesn't have time for one. That's not a problem, since Brenda's new job responsibilities keep her too busy for any sort of social life. But the day she is saved by a strange man who calls himself The Defender is the day her heart will never be the same. Lorne Palmer has loved Brenda since they were in grade school. Shy, introverted, and the middle brother of two over-achievers, he has never really approached her for anything other than to help her with her homework.
And to be there for her when her other boyfriends deserted her. It wasn't until he finally acquired his super powers and became The Defender that Lorne finally decided enough was enough. If he couldn't work up the courage to claim her as himself, perhaps The Defender could.