...Ensign Ro. Dishonorably discharged, given a second chance, then stabs Picard and crew in the back and betrays them before leaving starfleet for good. I hate that character with a passion.
She's my write in. Though I enjoyed the character, she fits the title. Not only did she get a second chance, but she got it on the flag ship and the renowned Picard gave her that chance.
Actually, it's a bit weirder than that. When she was DS9's chief of security, she was a Bajoran Militia officer. When she does get reinstated in Starfleet, she's made DS9's commanding officer, a position she still holds in the current novel continuity.
So, if we took the novels seriously, Ro got reinstated twice after insubordination (without being demoted) and then promoted 3 times afterwards.
I don't knock the novels, but this one strains belief a bit.
After committing both insubordination and treason, there's no way StarFleet would let her back in, let alone promote her.
I can see the Bajoran militia recruiting her, because they don't have a history, and they hate Cardassians, but Starfleet would never trust her again.