Sometimes, the best friends you can have are intangible. Whether it's a ghost, a specter, illusion, mist manifestation, or a special sub-species of familiar that exists half in another dimension. Sometimes, it's those allies who are non-coporial that you get along with best.

Especially is have contrasting Alignment types in your party.

Share a story about your non-solid friends.

So I created a character for a forum based RPG group based on the Mage system for White Wolf. He was a 1930's private detective, fedora and all, who packed a compact tommy gun, and a telescopic spear.

He was a special blend of Entropy and Forces, where the effects of each complemented one another, resulting in using chance on kinetic forces to ricochet bullets around corners, channel lighting through his spear, and a spell I named "The Machine God's Violent Death," where Entropy channeled Forces to ensure that machines and other objects (like cars) would experience the most flashy and permanent demise possible in the circumstances he used it in. This tied into the reason why the character traveled from his home brewed game dimension to the "Real World" this forum group took place in.

You see, the Technocracy was up to the "Manhattan Project" before the government was, and made a Magical Nuke. After ruining the Technocracy's plans and rigging the bomb for "safe" detonation, the Mage Detective found himself trapped with the bomb and used all his Forces and Entropy magic, sat on top of the bomb, and trusted his life to fate, hoping that somehow being at the dead center of the magic catastrophe would land him someplace safe. A very long of a long shot, but this is a character who's primary spell Focus was a Lucky Silver Dollar. Betting was in his nature. And the bet paid off, landing him through a dimensional tear into the "Real World."

Now, I told you that to tell you this. The character in question was Irish descent. He spoke his spells in Gaelic, and he had a magical guide like all Mages did in the system. But he got a perk where his guide was a little more "Real" than others. His was a fair (almost fey-fair) Irish lass who was his friend, ally, guide, and loving companion, all without ever having a real tangible body. She would speak in the whispers of the wind, phantasmally float through dreams as a guide, and once, after a multi-day training session in a giant mech-warrior robot (Yes, you read that right) in which he spent all his time not learning to pilot the suit, but to magically sense it's materials and control them as though an extension of his body, he entered his temporary living quarters and nearly passed out on the floor. His spirit guide manifested just enough to pull him in the right direction to collapse comfortable on his bed with a kind word about his impressive efforts and what might have been an ethereal kiss on the cheek.

Best. RPG. Companion. Ever.

A PC in the campaign I DM'd, a wizard named Gareth, managed to have two of these. The first was an ethereal green dog named Roderick. On one hand, he helped Gareth turn away from villainy and realize his true heroic potential. On the other hand, he had a tendency to do things like possess Gareth's body to have sex with an anthropomorphic giraffe. Later, Roderick was outed as a primal being predating even the gods, though he's retired.

The second showed up when Roderick temporarily vacated Gareth's head. She was the Iron Duchess, the spirit of a tyrant who ruled Gareth's homeland nearly 2000 years prior. She gave him invaluable tactical advice that saved his life in various fights. Later, she was restored to life, enslaved the setting's most powerful witch in a Faustian contract, and was appointed to the personal guard of the current emperor, who has fallen in love with her. In other words, things are going well for the diabolical tyrant.

I'll do it with a twist.

In this case, my then IRL best friend decided to play in a campaign I was running, using GURPS: Third Edition, Revised. This was a "supers" setting, and in a fit of madness, I was allowing everyone to do their own thing. It wasn't quite as bad as it sounded because we were still in high school, so quick 15-minute sessions allowed me to slowly maneuver most of them into place.

So, my friend created a (semi-retired) supervillain known as The Lord of Illusions (if this 20-year-old memory is accurate XP). His powers were based around manipulating light but I allowed a powerful secondary gift of... Insubstantiality. Which is just intangibility by another name so similar, I only noticed the difference a few years ago and had just misread the word the whole time. >.>

I also allowed him to buy a potent innate attack, laser beams from his eyes. Normally, such an attack would not work on Insubstantial beings while the user was "substantial", and couldn't work on "substantial" beings while the user was Insubstantial. There was an Enhancement that the GM was strongly encouraged to save for monstrously powerful NPCs to change that.

...

I allowed it. Of course, in the end my friend's character was defeated by the same foe that felled them all: burnout! GM and players; almost every person in our group felt like they ought to have their "own" campaign, and a few were trying to run two. Taking turns this meant at least one month between full sessions, and not taking turns caused other problems. XD

a long while back I played in a short lived game with a group that was normally a very big group (for once this group was three players and one gm) playing in 3.5
We were playing villians or at least not good people, I was a fighter, we had a ninja, and I can't remember the third characters class but we viewed him as the boss, he was our leader. Well along our journey and the many troubles we caused we came across a ring of three wishes with an efreeti trapped inside. First the boss attempted his three wishes all the while trying to get a tomb of wisdom, it did not go well. With the boss failing the Ninja proposed we just sell the ring and be done with it. Still my fighter while not brilliant was clever and charming. I decided I was going to get my wishes, so I put on the ring summoned the efreeti and asked him what he wanted. The GM made it clear that he wanted freedom but that not even with a wish could it be granted. So in exchange for two wishes that would work I would grant him the closest thing to freedom he could have. In the end boss got a tomb of wisdom, I on the other hand got turned into a golden half dragon (because who in 3.5 would suspect a golden half dragon of being evil) The deal was this I cannot put him back into the ring as long as I live, what I wanted was a more powerful form. The efreeti granted me one with a much longer life span than my human body would have to maximize his benefit of the deal. As the campaign went on he started healing me and even brought me back from death during the campaign, because we had become good friends. All the while my evil half gold dragon fighter lived his life as the muscle.

Still one of my favorite additions the anime had