According to TV Line, Raver will return for a multi-episode arc, which will bring Teddy back to Grey Sloan Memorial towards the end of the season. While there are no details on why she returns (or whom she's visiting), we can make an educated guess that sparks will probably fly with Owen (Kevin McKidd) again.
The last time Teddy was in town, Owen's sister had just miraculously turned back up in an army hospital after being missing and declared dead for years. Owen was simultaneously dealing with the death knells of his marriage to Amelia (Caterina Scorsone), so naturally they ended up in a lip lock. Before the kiss could go any further, Teddy pulled away and decided that she didn't want a romance between her and Owen to happen while he was still married, no matter what state that marriage was in.
Now though, Owen and Amelia are officially separated, which means the door could finally be open for Teddy and Owen to make that "best friends to lovers" transition.
Grey's Anatomy airs Thursdays at 8/7c on ABC.