Brennan - Invasion Profile

At the end of Season 1, Bren was 16, dating M'gann, and had little control or knowledge of his powers.

Now that the invasion has begun, Brennan has aged; a lot. He's 21 now, older and somewhat wiser. During the timeskip, he's buffed up quite a bit, trying to fit in with the big guys on the team. He's still got the glasses, but has upgraded a bit to some stylin' Ray-Ban wayfarers. His hair is shorter, more like Red Arrow's (circa S1) and a bit darker.
Bren's also fighting to keep M'gann's interest, especially with the hulking jerkwad of an Atlantean called Lagaan around. Eventually, Bren breaks it off with M'gann, because of her drifting attention, Lagaan's constant flirting (worse then Wally's, in so many ways) and because he didn't want to suffer through the pain. Anyway, he and Conner are a lot closer now, and Conner is usually the one Bren goes to, to let off some steam. They are the unlikeliest of best friends.

Before, Brennan probably would have gone to his big-sister figure, Bennie, but unfortunately, she became more withdrawn and left the Team just as Bren and M'gann broke up. They used to call each other about once a year, and Bren tries to get in contact, but eventually just gave up. Eventually though, he is the one to bring her back into the hero business. He's also close with Cheyanne (Shatter) and she's been less then helpful with his relationship issues.

His costume hasn't changed at all, though he's got more control over his powers. Since working out and developing his own muscle power, Comet doesn't need much additional help in kickstarting his powers. However, Superboy is always on hand to help out. Comet also has more control over the energy he releases, and can now channel it in different amounts in different places in his body, eg. more strength in kick, less in punch.

Comet was not offered an invitation to join the League, and remains a senior member of the team, though he's often assigned to the Gamma squad on missions. However, after striking up a friendship with Zatanna after she officially joined the team, and once they began dating (about a year after his break-up with M'gann), she has been advocating for him to join the League. They're happy together, happier then when Bren was with M'gann. Zatanna makes him laugh and keeps him on his toes, while he keeps her grounded and they mature together.

Brennan shared the secret of his powers with his parents when he was 19. His father kicked him out of the house and destroyed all ties with him. This angered Ainslee to no end, and she moved out, leaving Brian on his own. Bren still lives with his mom, who loves Zatanna to pieces, and while she worries about him, she knows and understands that despite his mysterious powers, he is still her son. Brian fell from grace after the scandal with his family (the press showed that he simply kicked his son out, and his wife left with him; people didn't take kindly to that), and left politics. He remarried and has three step-children who Brennan has never met, and doesn't want to meet.
In short, Bren's matured, learned control, and found himself a kick-ass new girlfriend who loves him.