A good friend has a [name_m]Patrick[/name_m] and he only goes by [name_m]Patrick[/name_m]. If anyone tries to call him [name_u]Pat[/name_u], he corrects them. I know of two other Patricks, both adults, one chooses to only go by [name_m]Patrick[/name_m] and the other goes by both (Patrick and Pat).
Thought of a couple nicknames/pet names, Patch and Patches.