Sounds good. A possible reason for him being there is that he was delving in the area directly above Hollow Bough in the Underground, a multi-leveled dungeon called Mercy Dreams, either alone or with a party that he was then separated from for one reason or another. Tonight's update will include an introduction of Hollow Bough and setting the scene for the first of the three weeks we'll be spending there, so once you've seen it you can work on an OP to introduce the Jester. If you want you can expound on what he was doing in Mercy Dreams (looting, killing monsters, trying to hunt down the area's demonic-looking boss monster Ten Piedad, etc) his other three party members, and what happened to him (or them) prior to having him stumble onto the scene with the team.