Ok,
@EmperorV, what I know, hopefully keeping it short.
As Monroe mentioned, when you try to even touch someone while out of body, it can become explosive. This protection isn't, in my humble opinion, something your buddy can override with the desire to volunteer. And no, I haven't determined what might be behind this exact lock, block, or filter system. There are many of these lock/block/filter systems in place, as if this were by design. Some of it is protective.
You can merge together during dream practices, and/or share the same dream and dream landscape. So you can be lucid together.
These differences are also the reason we separate the descriptions between out of body, astral, lucid or dream body. There are more systems than this, but these appear to be the most common and have common terminology. The variations of experience, even in the known, are extreme and cross over.
There is a configuration where people become one, and I'm not a fan of that cesspool, but you lose your own identity and merge or blend into this oneness woo woo system that is like a pee pee warm love pool. Some people appear to like it, so to each their own. In that scenario, you would likely lose your own intent and will to the giant pee pee pool of love... barf.
I have not attempted to touch anyone else in an out of body state.
I have heard that some dead people have stepped into other people's bodies after that owner died and left, and the body was revived and that person stayed, without knowing what actually happened after that. I assume they assume that identity and live on.
There are the tales of shaman and others possessing animals, and often if that animal dies, so do they.
There are also the familiars where they can loan you their sight or more.
Psychics that can see and feel from the perspective of the victim or perp, whether that is some stored history or akashic, and likely a bit of both. Then the possessions by entities, which would say it is totally possible to do, but I'm not an entity so I couldn't say what method is involved in that.
There are also the facts involved in herd poisoning or intoxication, where one instigator or influencer can control the mental and emotional rage of entire crowds, and this can also be seen in some concert settings where people lose themselves and become controlled like the lemming puppets that most of them truly are. There are the possessions of the holy spirit in some religions, and the possessions by spirits in many Hoodoo practices.
So, we have a lot of options and tales.
If you accomplish this, please certainly let everyone know.
The first step, of course, is to be able to step out and control the experience, which is pretty rare, even with those who are quite adept at it.
I'm a dreamer or dream walker mainly, and that bleeds back and forth between lucid, out of body, astral, and just bits and pieces of perception that can perceive banal and stupid future events at random or experience things because of that form of perception. I haven't figured out what good most of this skill is, except for entertainment and shocking the people who are dreaming into understanding that there is more to reality than they realize. Much of these experiences are sudden, uncontrolled by my ego consciousness or my own intent, and are obviously being steered by different formats of separate altered states or personalities of an ethereal nature. So, alignment with these other parts of ourselves means losing the waking ego part of yourself and letting these other parts steer the boat, and that usually means you lose your own will and intent in order to be able to operate and perceive in these other formats. Aligning your intent with those parts of yourself that can step away from the physical body is a major esoteric feat, and also very rare. Like the "Not my will, but yours be done" idea. Surrendering.
So, short form, even if you do get out of your body, the part of you in control and experiencing this is not likely going to be the same you that wishes to merge with your friend, and you will likely end up doing other things instead.
