1d20 + 14 = 33.

Dergaix is more aerodynamic than a flailing Goblin.
If he wants to stay nearby he can do that.

Dergaix would like to use his breath weapon.

2d10 fire damage, DC 15 to half?

Nub has a +3 Base Reflex Save (Rogue 2)
Nub has a +5 Dexterity bonus (20 Dexterity)
Nub still isn't wearing any armour.
Nub has +8 to Reflex saves.
1d20 + 8 = 20.

Nub passes, and can take half damage.
Nub drank a potion of Resist Energy (fire) while he was inside the backpack.

2d10 / 2 - 10 = - 3.
Nub is fine.

Nub would like to attempt, in order, a DC 30 Linguistics check to express a desire to submit to this dragons will via Interpretive Dance, a DC 20 Acrobatics check to perform said Interpretive Dance while in freefall, and an opposed Bluff check to be believed about it because even now he would still in fact be lying.

Linguistics is a Trained-Only Skill.

It might be a class skill for Rogues, but you still have to actually put a rank into it at some point. You never learnt any Linguistics, so you're not allowed to even attempt the check.

Nevermind then. Nub would like to grab the Bag of Holding, climb into it, and then stab it from the inside. He doesn't like being here any more and would rather take his chances on the Astral.

It's not within reach. Dergaix is still holding it in his back claw.

Can Nub stab the Dragon?

Dergaix recently learnt the advance technique of staying within reach of his Breath Weapon but out of reach of melee attacks. He's hoping to try it out on a different opponent in a new setting, to see how general the strategy is.

As long as you don't grow wings and he keeps passing his Fly checks, no, you can't.

Can Nub shoot the dragon with a poisoned arrow?

Sure. He's only 15 feet away.
Nub has a +1 Base Attack Bonus (Rogue 2).
Nub has a +5 Dexterity Bonus (20 Dexterity).
Nub has a +1 Size Modifier (Small).
Nub suffers no range penalty.

Nub has a +7 To hit. Dergaix has an AC of 19.
There is a 40% chance to hit, in which case you can deal 1d4 damage.
You will average 1 damage / round, killing Dergaix in approximately 6 minutes.

As for poisons, he has a +7 to saves, and your best options are mostly DC 11 and would take at least 3 effects to incapacitate him if you get lucky.

Also you have approximately 3 rounds before you hit the ground.

It doesn't even matter what I say, does it?

Nub shoots.

1d20 + 7 = 8.

Nub misses.

Dergaix is confused why the fire wasn't effective. Maybe Orcs are all immune to fire? Mother did seem to think it wouldn't work on them before.

He'll have to try his luck in melee with something besides his sister eventually, now seems as good a time as any.

He intentionally falls more towards Nub and makes a bite attack.

1d20 + 11 = 12.

Nub has an AC of 10 + 0 + 5 (Dexterity Modifier) = 15.

Miss.

 "Dexterity Modifier" Implies Nub is trying to move out of the way.

Why should he bother? He's dead either way. He should just go limp and wait the universe out as he falls to his inevitable death.

Fine. Bite lands.
1d6 + 4 = 5.
Nub has 11 - 5 = 6 hit points remaining.

Nub continues to wait for death.

Dergaix is starting to suspect that this creature is not in fact a baby Orc.

For one, it appears to have more training, equipment, and the evidence of past misadventures than one would expect.
For two, it lacks the tender fattiness that one would expect, especially of one that would grow to be as big and strong as the Orcs he saw before.
For three, it appears to have accepted its inevitable demise. Mother always Suggested to him "big dragons don't cry so shut up", so probably this one is grown also? Which implies it isn't an Orc, but some other creature.

Also it tastes bad. Dergaix does not actually want to eat it, even cooked.

Dergaix will attempt a grapple.

Against an unresisting opponent, it can't fail.

... Has he really given up on fighting back?

The grounds starting to get close.

Dergaix will attempt a DC 10 Fly check to arrest their fall.

With a +14 to Fly that can't fail, except for how Nub, his gear, the entire contents of the Bag of Holding and The Bag of Holding itself are a Heavy Load for a Small Quadruped with 17 Strength. Dergaix will have reduced fly speed with this much weight.

... How does that work? They weren't this heavy on the way up.
Oh it's the bag isn't it, it weighs the same amount whether it's full or empty.
... Is that how bags work? Dergaix is genuinely confused here.

He'll think about it later.

The not-Orc doesn't seem to be the same kill-stealing creature it was a few minutes ago, but maybe it's just bluffing.

Dergaix is a cautious wyrmling. He'll try dropping it from high up a few more times to confirm.

Did he just abandon hope and then be saved anyway?

Nub almost actually starts hoping again, before realising that would be silly. The dragon is just toying with him. He'll be dead soon either way.

Few creatures are more cruel and fearsome than the mighty red dragon. King of the chromatics, this terrible beast brings ruin and death to the lands that fall under its shadow.

Red dragons often keep humanoid slaves, most often human and elven maidens, which they treat as beautiful and delicate but replaceable additions to their hoards. When these slaves become old or injured, they are typically eaten. Other slaves are instead kept to expand and maintain the red's lair.