well, on this one...
...PS: How the heck does a dragon fail a Fort save?! They use the fast save-progression, and they've got an insane Con-progression! Maybe I'm suspicious, but I'd be wondering "Nat 1, or DM fudging...?"
Seriously, he shot three arrows... and the dragon actually rolled a Nat 1 on the third arrow.

The GM usually doesn't fudge rolls, he lets them stand for good or ill. And whatever the poison was, it was especially virulent and had some special nastiness to it. We don't have any more, and the ninja was saving it for many many sessions for something useful.
We were all shocked, we didn't even know the arrows were poisoned. We kind of expected to die, and then it just rolled over and crashed into the ground.
Later the GM said he wasn't expecting us to kill it; we would just fight, and eventually someone would retreat (us or him).
It turns out it wasn't necessarily a great option, as it was a captain of the high guard and the Queen's favored (there's a dimension shift occurring that we're trying to reintegrate the dimensions -- and the dragon city is right over top the tengu city we were in, but we didn't know... and somehow the dragons got caught in a warp and thought the tengu had invaded THEIR city), so they might have actually been willing to talk to us, but if they find out we slew the Queen's favored... that would be very ugly.
So while we killed a dragon, it might bite us in the butt later.
--
I will state that Jeremy does seem to like to toss in really powerful stuff, to see what we do with it -- whether it kills us or kills the other guys. I mean, the ninja found this deadly poison; and Sumiko found both a balor stone and a great wyrm stone. She didn't even know the dragon stone was a great wyrm until very recently, and here she's been carting it around for many sessions not trying to use it. (He says I can try to talk to the dragon, but I'm kind of scared to. There's the possibility it might end up controlling me, versus me him.)
I think he likes to throw in stuff and see what we do with it, and if we don't follow up on something, he doesn't say a word. He'll also put in some really nasty stuff, if we're dumb enough to do it... so with him, we just can't tell whether we're going to gain something good or die horribly. (This past week, there was an almost impossible-to-crack dwarven vault that I knew was probably protected in every way possible; Sumiko considered teleporting in but was hesitant to do so, someone in the group taunted her, and she immediately tried to do it anyway Because Roleplay. She had to make a Will save and got a 33 because she happened to have a bonus on it at the time and simply didn't go anywhere... Through a high spellcraft roll, I found out the DC was 30, if she hadn't had the bonus she would have failed, and if you failed that save, the Vault would teleport you 8 leagues out to the ocean floor into a small metal box surrounded by a sphere of anti-magic. Oh good grief!)
He usually also knows character builds really well and as a player tries weird combinations and also has the highest character mortality rate in our group. it's kind of funny... but it never seems to bother him.
Anyway, yeah, he likes to put a bunch of fun unlabeled toys in the sandbox that might help us as well as kill us, then lets us do what we want and plays it out.