His appearance schedule is about to get 'mad'.

Perhaps the best guest star yet on ABC’s hit freshman fairy tale drama Once Upon a Time happened to be Sebastian Stan this past Sunday as he was introduced as a new take on the Mad Hatter called Jefferson. Proving to have monumental importantce towards the main character’s development in believing the fairy tales, Stan’s character was quickly zipped away with a mysterious question leaving his fate hanging. Now, it seems fans will have their raved about character back in the future…and a very close future, at that.

E! Online reports that Stan’s guest starring role isn’t simply for one episode, and his character of Jefferson will return in two episodes before the season finale in May. Jefferson is one of three confirmed characters who have retained their knowledge of the fairy tale past in the real world, and with that development, he’s very much a major character in the context of the series. However, his fate was left unconfirmed after a finale that resembled a certain scene from 300 with Mary Margaret. Furthermore, it’s uncertain if Jefferson will return in strictly flashback, or if he’ll return to Storybrooke.

This isn’t the first major guest star of the series that will return multiple times in the series’ first season. Emilie de Ravin made a quick return via flashback, after her Beauty and The Beaststory with Rumplestiltskin, with a tale that involved the tale of Grumpy. Writer for the show Jane Espenson has confirmed the character will also be returning in the season finale in two short months, but it’s unclear again which storyline the guest will appear.

Once Upon a Time airs every Sunday at 8PM on ABC.