Why Olan has so little TP?

[Kain]

Does it burn out when he walks? I have rested party and he still has about 15 TP only.

[Daverball]

TP work differently than SP, you don't keep them between battles, you earn them by doing normal attacks, using items or getting hit, there's also a few items and abilities that give you instant TP boosts.

[Kain]

Ah, great, thanks.

[Kutan]

You can't carry TP between battles. You'll always start a battle with a random amount; somewhere between 5 and 20 it seems like.

You gain TP by using the character's topmost command, and by taking damage (the latter being much faster). There's also a consumable that you can use in battle that gives you TP, if you can afford it.

Edit: Oh, come on Daverball, again? I can't keep up with you! <3

[Kain]

Another question, why sometimes it seems enemies hit themselves? Live Charmy, it seems like it hit itself for 1000 HP.

[Miles Bluefalls]

He's probably been afflicted with the "ticked off" (can't say because censor) status.
There's a chance they'll hit themselves.

As for TP, there's a few characters that can restore the TP of other characters in battle. They're really worth keeping around just to spam that, because some of the TP-reliant characters have REALLY good moves that are otherwise expensive.

[Kutan]

If it's a nice round number like 1000 HP, he's probably afflicted with a damage-over-time status effect. At the end of everybody's turns, enemies take damage from stuff like poison, bleeding, and burning. That might be what you're seeing.