This may come as shocking news but Marko Marin has been out injured or semi-injured for most of the last four months, so he's been spending his days being all buddy-buddy with Ivan Rakitic and letting Hyrule go to the evil wizard Agahnim.
After an excellent pre-season, Marin picked up another strain of hamstring-hanta virus in October, then had problems off-and-on with his thigh. At some point, he even ventured back to London to get himself checked out by the Chelsea medical staff, presumably under strict quarantine conditions lest he infect the whole squad with further communicable muscle strains like that one time he cast his hamstring-hex on Daniel Sturridge.
But fear not, brave princess Zelda! Marko Marin is back, baby! And he might just stay in Seville and guard you for the rest of eternity.
"If both Sevilla and me are happy to stay I can stay here forever."
"We'll see what happens in the summer. The first is to play, being fit and helping the team in the end of the season and then we will decide. If the fans want, Monchi (the sporting director) wants and the coach wants, why not?"
-Marko Marin; Estadio Deportivo via IB Times
It should be emphasized that Marko doesn't expect a decision one way or the other until the summer. It probably wouldn't hurt his transfer prospects if, rather than just making the odd cameo off the bench, he actually managed to get back to full match fitness. And then stay match fit for more than five minutes.