In the rich text editor:
@MeruMerurun
In a comment:
[MeruMerurun](https://painted-relics.com/user/MeruMerurun)
For Names and Avatars:
In the rich text editor:
%MeruMerurun
In a comment:
[![MeruMerurun's Avatar](https://painted-relics.com/images/avatars/452.png)](https://painted-relics.com/user/MeruMerurun) [MeruMerurun](https://painted-relics.com/user/MeruMerurun)