The idea I'm currently toying with is something like if you mixed Yachiru and Shiro-chan with Mayuri.

[b]Intro[/b]: [i]Young Captain of the 12th squad who is far less experienced than her peers, but was given this rank from the now deceased previous Captain and accepted by the other Captains due to her recently developed Bankai and exceptional strength relative to the other candidates. She has inherited more than the leader of R&D's title, she's also inherited tons and tons of research, all of which had never been properly sorted or disclosed to the public.[/i]