May I ask a pedantic point, please?
Having a full grid and the relevant characters, a potential conflict has arisen. The letter where the clued entry for one of the characters meets the periphery could be used as the starting letter for the title of the next character. Alternatively, this letter could simply function as the character’s last letter, in which case it would have to be followed by the first initial of the surname. I favour the first. Asking for a friend.