PC is a 5th level wizard starting a Lovecraft / Mythos scenario. It's been established he has a Mythos-related backstory, but no details have yet been filled in -- at the moment, it's a "Noodle Incident" type of thing. I have some ideas, but I'd be interested to hear what the group mind comes up. Here's what I've got so far:
-- incident was Mythos-related
-- incident was horrific
-- one or more innocents were killed. The wizard PC did not *directly* cause the death of the innocents, but he absolutely feels complicit and guilty.
-- the wizard PC used to be your classic arrogant jerk wizard who is all about the pursuit of KNOWLEDGE
-- I think the wizard PC had one or more bosses or patrons (who were probably a lot more evil, and who may or may not have survived).
And at the end of the day the wizard PC staggers away, sanity barely intact, plagued by terrible guilt, recurring flashbacks, and the Spooked drawback. Which, as everyone who has ever played Call of Cthulhu knows, is about the best possible outcome for surviving a Mythos incident...
Several of Lovecraft's stories involved someone investigating something to do with one of their ancestors. You might find inspiration in The Case of Charles Dexter Ward or The Rats in the Walls by H.P. Lovecraft (plot summaries in links).
The fate of most 1st-level characters who encounter Mythos-related scenarios is an unpleasant death (if they're lucky); IMO, there's a reason that even Paizo's Mythos AP doesn't bring the PCs into contact with much Mythos-related stuff in the first module. Add to that the fact that 1st level wizards are almost improbably squishy and you're probably looking at an encounter that took place once he'd reached 3rd level. This might also go a long way to explaining the arrogance - 1st level wizards run out of spells a lot and need to get used to running away (at least, in my campaigns; YMMV)... but a 3rd level wizard knows just enough to be a real danger to themselves and others ("I can cast Scorching Ray! Tremble, ye mighty and despair!").
So... suppose your wizard has reached 3rd level, which means he's been away adventuring a bit and accomplished a few things. He comes back to his hometown, possibly with a slight swagger in his step, and finds that something is off. Not much, just a bit, with someone close to him. Perhaps his nephew/niece has joined a religious group? You know which relative I mean - he doesn't have a lot of time for family, they get in the way of important things like studying, but this one (whose name he gets right more than half the time, which really shows he cares) isn't as impossibly stupid as the rest of them and even occasionally asks some questions that almost begin to appear intelligent. Since your wizard left town, this niece/nephew has started looking for answers elsewhere.
The religious group itself is fine: full of nice, smiley, amiable people. Harmless, really. But what a waste of a mind! Surely the thing to do is to accept niece/nephew's invitation to join them at their next meeting. After all, your wizard has a keen intellect: really, all that's needed is to expose these misguided people to the razor-sharp clarity that is pure reason.
What could possibly go wrong?
What's really going on:
The religious group is [SURPRISE!] a front. Or no, that's not quite right. It's a lure. Proclaim you have answers and you will attract three kinds of people: those looking for simple solutions to an otherwise complicated life; those like nephew/niece, who are bright enough to have questions they can't get answered from the usual authorities; and, ahhhh, if you're very, very lucky and/or have made the correct sacrifices/propitiation to the wrong sources, you will attract people like your wizard: someone bright enough to see through the initial guise, and juuuust sharp enough - as the saying goes - to cut themselves.
Welcome such people. Be open with them (away from other ears, of course) that there is more to the group than meets the eye; but explain that such initiation is not for the faint of heart, that they may discover more knowledge than they can handle.
And, if you do it just right, those people will volunteer to be initiated...
Perhaps your wizard had a friend/rival and they egged each other on to more and more dangerous things. Eventually they tried constructing a maze as a trap/lure for a hound of Tindalos; your wizard had cold feet at the last minute and tried to stop the rival finishing the construction. Whether for that reason or simply because that sort of thing is insanely dangerous the hound arrived, escaped, tormented the two like a dog with a rabbit and finally killed someone else before leaving for some place with better angles.
The rival survived and certainly blames your wizard. Some of the guilt was served up by people who took the rival's badmouthing as fact.
Wizard's master found an ancient 'elvish' portal to 'another world'. The portal is mostly in tact, but was missing some key elements. Our young apprentice helped to enchant the replacement crystals the Wizard planned on using to repair the portal.
The expedition included several well known adventurers, sages, and other arcane dabblers. All of them were eager to see this new world. The portal opened into an abandoned stone temple of some sort. Wandering out of the temple it was apparent that it was located underground. The natural lava tunnel was a riddle honeycomb where shadows coiled around at odd angles.
While exploring the caves a low rhythmic sound could be herd. Perhaps it was chanting? The sound became more distinct as the party wandered eagerly towards the sounds. Before the explorers could locate the source of the sound it changed to high pitch laughter, crying and hysterical wailing from dozens of voices.
And then silence.
Then everyone could feel a building tremor through the stone. And the sounds of many things scraping over stone. Uncountable numbers of things and a constant droning chittering sound.
It isn't clear who started first, but our young wizard found himself running in terror from the sound along with several of the other servants and porters from the expedition. In the distance he can hear a few muffled explosions and the shrikes of terrified people.
As he runs through the tunnels wriggling black tentacles the size of an arm appear from holes in the walls catching onto the people running beside him. The trembling grows strong enough that he trips and stumbles in his attempts to return to the portal. As he progresses there are less other people with him.
Finally he makes it through the portal. He was the first, and he immediately shatters the crystals to make sure the things do not get him as well. Only after this is done does he think of the consequences.
I've been thinking about this. Still working out details, but I think it involves the Mi-Go. And a friend of his master's, a jolly fat man who goes by the name of Herr Glaezend. ("In the common tongue, I suppose that would be... Mr. Shiny.")
