Should you open Patches’ second chest in Elden Ring?

gamepur.com:

If you decide to accept Patches’ surrender and forgive and forget in Elden Ring (and we reckon you should), then he’ll become a merchant, who you can buy items from and sell items to, as well as asking him about specific topics. The first topic you can ask Patches about is “About the bandits”, to which he will respond by rambling on about the bandits in Murkwater Cave. Once he shuts up, you’ll then be able to ask about “That chest…” He’ll acknowledge that you are wondering what’s inside the treasure chest, and tell you that it’s nothing too special, just something he’s saving as thanks to a very valuable customer. Does he mean you? He attacked you when you opened his first chest, but does Patches’ second chest contain a reward for sparing his life?

No, it doesn’t. You should not open Patches’ second chest unless you want to be forcibly teleported to the other side of Limgrave. The chest actually contains a Transporter Trap that sends you to a location in Limgrave East, southeast of the Mistwood Outskirts Site of Grace. If you try to fast travel after being ensnared in the trap, then you’ll get a message telling you that you can’t until you’ve rested at a Site of Grace. As mentioned above, the nearest Site of Grace is the Mistwood Outskirts one by the road to the northwest, and it’s easy to get to it safely. If you return to Patches again after falling into his trap, he’ll express surprise that you’re still alive, but he’ll still trade with you as normal.