[D&D 5E] Passive Investigate, and Investigate as "Deduction and Memory"

I've been having a tough time conceptualizing what Investigate is for in 5E, and thinking of it as "Deduction and Memory" has finally made me feel better about it. Here are some outside-the-book applications I've thought up:

The first and cleanest use of Investigate is as the proficiency that applies when the player goes "dammit, what was that merchant's name again?" and the DM says, "roll int to see if you can remember."

What is passive Investigate for?

Your DM can cater descriptions to fit your party's passive investigate scores, and your party can use investigate actively to piece together particularly puzzling pieces of the story. As DM I sometimes wonder how generously to describe a scene, and passive investigate scores solve this.

The difference between low and high passive investigates is something like this:

[low]There's a man lying dead on the ground in the northeast corner; the door to the west is broken down.

[high]The man was trying to hold the door shut, but something burst it in, killed him, and tossed him across the room. Based on the wounds, it looks like it was probably one of the trolls you've been hearing about. Also, you realize the man matches the description on a wanted poster you saw back in Waterdeep.

Without investigate, if the players don't think to ask about the man's identity or circumstances, they miss out on information. But characters who are trained investigators (or just intellectually sharp) can pick up on these details automatically. Things like NPC motives or story connections that only make sense if you've been paying close attention can be given as freebies if somebody at the table is role playing Sherlock.

That's what passive investigate is for, and that's the other half of the Observant feat, which I know has been causing a lot of internet head scratching.

Investigate vs Perception

Finally, Investigate, by the rules, can be used to find hidden doors and treasures, which overlaps with perception. In my mind, investigate determines what a character can deduce about their surroundings, while perception determines whether they notice obscure details. Perception could tell you that there are two candlesticks on the mantle, and maybe even that the left one looks cleaner than the other; Investigate could tell you that the candlesticks aren't symmetrically placed and that the left one could, based on its position, possibly be attached to a latch lever inside the wall. You could find the secret door with either skill, passively or actively.

Based on these realizations, I'm going to start using a lot more skills passively too, especially Arcana, Nature, and Religion.

GM's Journal: Kingmaker - Pre-Game Character Building

Every group approaches character building differently. Even the same group going into a new campaign can merit a different approach. Going into Kingmaker, I knew that a large portion of the campaign would be open-world sandbox type exploration with a significant portion of the PCs wealth and xp would come from random encounters and the like. What this told me was that there would be plenty of room for me to add in personal quest hooks and introduce NPCs to further engage my players.

So when laying down the requirements for character building for this AP, I tried something new. Beyond the standard race, class, and sourcebook considerations I asked my players to write up a background for their characters. Specifically I wanted them to address the following: Who are you? Why are you an adventurer? What are you doing in the River Kingdoms?

As an added incentive, I allowed my players an additional 1 gp per word of their background write up (to a maximum of 500 gp). I've never tried offering such an obvious bribe to players to get them to give me more than just a stat block for their characters. And to be honest I've never really felt like I've need to. But for this I was hoping that my players would help me seed the adventure with NPCs or personal goals of their own devising that their characters would already have a vested interest in.

My players didn't disappoint. After reading their backgrounds I have side quests and plot hooks enough to take us well into mid-level adventuring. I feel like I have a solid idea what will and won't engage my players' characters, what will stir them to action, what will make the shy away. And all before a single die has been rolled.

So who do we have to fill our roster?

Adem Margrave - a young nobleman from a middling Brevic family. Adem found his true calling in lyric and song. An academy trained minstrel, he journeys with his friend Garren and the knight's peculiar wards.

Balas and Calidrel Orron - half elf brothers and twins at that! Balas is a brutish type while Calidrel's blood is further muddled with all kinds of sorcerous mischief.

Garren Stewardsson - a human knight and equine aficionado. Though he's now well into middle age, Garren has sworn to protect the Orron twins with his life.


Marius Ranicot - another human knight. Marius armors himself in steel and bluster, projecting the very essence of a brash cavalier. But perhaps there's more to him than bravado.

Sergey Popovitch - a human scholar who's spent most of his life dedicated equally to both arcane and divine pursuits. After decades of empirical study he's finally decided that some fieldwork might be in order.