How do you guys handle players with really high passive perception? I have one that got the Observant feat and high Perception already, giving them 21 Passive Perception at level 1... How the hell do I deal with that!? They spot everything at all times...
It isn't really that big a deal. I have found that overall, perception bonuses for the most part fail miserably to keep up with stealth bonuses. In practical terms this makes most competent perceptive adventurers on par with a blind man when attempting to spot hidden creatures. A 21 passive is REALLY good but once mid levels are reached its a fair bet that this character won't be able to find the party rogue even half the time, and you can change that to never if the rogue ever gets a cloak of elvenkind.
So don't worry too much.
Something that can help, while still giving the player the benefit of his resources, is to ignore the "official" method of using Passive Perception. Rather than using the passive score against a passive DC, which creates a ton of problems in it's own right, turn the DC into an active check with a bonus equal to the DC -9 against the player's passive perception. The player will still notice just about everything (as they should), but occasionally you'll roll high enough to cause them to miss something. This will keep a bit of spice in the game, while still granting the player their properly earned benefit.
Oh, and for those that consider this a houserule (because RAW!), this is how Mike Mearls suggested using Passive checks long before Perkins "clarified" the use of Passive Perception.
A little to pvp focused![]()

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.