Beguiler Fun

[TheAmazingOP]

So I started a new campaign with some friends recently and right now I'm playing a Beguiler 3, soon to become Beguiler 4 (with access to 2nd level spells).
I have 16 INT (meaning a bonus 1st level spell and 2nd in the future) and Spell Focus as feats for both Illusion and Enchantment schools, making my spell DCs 15 for 0th and 16 for 1st, +1 to each with cloaked casting. Considering I'm a strongheart halfling, hiding comes naturally with the bonuses and 16 DEX. As for my Advanced Learning, I took Distract Assailant, which is a swift action spell that leaves opponents flat-footed until their next round (which is also useful for cloaked casting).
Here's the situation: The party consists of
Strongheart Halfling Beguiler (me)
Half-Giant Gladiator
Elf (custom class) Ninja
All 3rd level
We're all Chaotic Neutral, and the Gladiator and I have become friends over time while a bitter rivalry brewed up between the Ninja and I, eventually leading to the point where he tried to slit my throat at night (which was thwarted by a little magical construct I had befriended). He seems to have backed off for now and I feel secure enough that the tiny construct and the Gladiator have my back, but just in case anything interesting happens, I want some ideas on how to deal with him.
The ninja class the DM created is very mediocre. The main features are that the ninja starts with two attacks, +1/-1, and now at 3rd the ninja is at 2/0. The class also gets a pretty good mix of fortitude and reflex saves (can't remember right now) but the will save is horrible, maxing out at +6, and right now he is at -1 due to his bad wisdom modifier. In addition, ninjas get special "abilities" they get to pick every 4th level, such as something called counterattack. He picked an ability which allows him to triple his DEX (up to a certain point) leaving him at 22 AC. He is also proficient with most oriental weapons, so he has daggers, shurikens, and a quarterstaff.
The main downsides of the class are that they cannot wear any armor, and they don't get very much between the 4 levels in which you get abilities.
So you can see that I have a great advantage over him, seeing how I can disable him through will saves and remove his DEX (thus removing all his AC). This is my first time playing a spellcaster, and considering illusion/enchantments require lots of imagination, I'm asking you guys to help me in toying around with him (but not overboard, like killing him).
Here's the spell list: http://www.imarvintpa.com/dndLive/Index_Class_Desc.php?Class=Beguiler

[Psyren]

PvP is best settled through an out of game conversation. If he insists though, tell him you'll knock him out/blind him and cut his throat.

[Phelix-Mu]

While messing around between characters can be some fun, it can also degenerate into bullying if one person consistently has the upper hand, which can ruin the character for the one that becomes the whipping boy, so to speak. Beware the irl dynamic between yourself and the other player. However, if it is a friendly rivalry, then all sorts of fun can be had with illusory effects and some of the more tame status effects. Consider illusions placed in the lavatory at the local inn, making the half-orc waitress look like a pretty half-elf wench, or humorous illusions placed in the mirror in the room of the ninja.

A slight downside of this is that you also need to be confident in your sneaking abilities. Invisibility can be used to excellent effect, particularly since many practical jokes can be executed without forcing the invisibility to end. You mentioned the ninja had bad wisdom, though, so maybe beating his Spot/Listen won't be too hard.

Avoid hardcore psywarfare, though. Depending on how tightly wound the ninja is, it is often easier to unravel CN characters than you might think. Subtle voices in the night, for instance, seems tame, but insomnia and paranoia are widely open to how the player wants to role play, and can lead to even more craziness between characters than is already present.

[TheAmazingOP]

Don't worry about any full blown killing/bullying/anything like that. Just something to teach him to calm down and show I can get the upper hand if he tries to mess with the party. A little mischief (like Phelix stated) is also welcome.
Any ideas, really. We're a casual group and fun is fun.

[Mr Adventurer]

Charm Person?

[TheAmazingOP]

Charm Person?

I know I can use the spell, but what I was looking for was more what to do with him after I had charmed him, not how to get him to bow down.