Out of curiousity, has anyone considered the possibility of mentor spirits for adepts? Instead of helping with magic, they would further improve their physical abilities. (If you had a second person connected to your eyes and ears, you'd be a lot harder to sneak up on). These helping spirits would be in two classifications: Symbiotes, which would apply to free and/or ally-style spirits and other sentient spirits, and Aspects, which would apply to elementals and nature totems.
However, having a spirit integrated into one's self might have its own problems. Aside from being rather difficult (this would be an initiate-only option), they would require additional resources to sustain themselves, such as a point of Magic (a la' ally spirits), a percentage of the runner's karma, or simply a heck of a lot of food.
Also, I would restrict characters to only one aspect, symbiote, or whatever at one time, unless extenuating circumstances apply.

Here's my example:
Aspect of the Mighty Bear:
A possibility for some of the more violent, close-combat adepts out there, the Aspect of the Mighty Bear would give the character berzerk strength in exchange for a temporary loss of reasoning ability.

Rules:
Acquiring the Aspect:
Acquiring this aspect requires initiation. One point of magic must be sacrificed; this point of magic is regained of the Aspect leaves the character's body; after including the magic gained from initiation, no magic is gained of lost. This Aspect also counts as a Metamagic. The character must be decidedly bloodthirsty, only rarely retreating from hand-to-hand contact, and have a close-range combat skill and strength of at least 4.

Benifits:
- +1 to Body at all times.
- Shaggy body hair all over body, allowing the character to remain unbothered by low temperatures.
-Healing times are reduced to half normal. The character can heal some wounds that would normally require medical attention, such as large gashes.
-When Berserk(raging), character gains an additional +2 to strength.

Penalties:
-Character would go into a rage in a similar manner to the Wolf shamans of SR3. The rage would only be triggered by close-quarters combat.
-Character would have to eat twice as much food as normal.
-Character would take double magic loss from cyberware as long as the spirit inhabits him or her. (Note that this does not apply to essense loss, only magic loss.)

To give another example:
Symbiote, fire
A symbiote fire spirit is just that: A fire spirit that inhabits a physad, granting great power in exchange for spiritual energy.

Acquiring:
Acquiring a fire symbiote requires a lengthy ritual costing five karma, or can be considered a metamagic during initiation. One point of Magic must be sacrificed; this Magic may never be regained.
A Fire Symbiote requires a reaction and agility of at least four.

Benifits:
-An individual inhabited by a fire spirit gains partial immunity to fire, reducing any damage taken from fire by two boxes.
-Fire damage may be added to unarmed attacks, increasing the DV by 2.
-The Reaction score of a character inhabited by a fire symbiote is increased by two, and the agility score by one. In addition, one additional initiative pass is gained.

Penalties:
-One in three points of karma must be sacrificed to the fire spirit.
-A character inhabited by a fire spirit must eat double the normal listed amounts.
-A character inhabited by a fire spirit has a body temperature of approximately 110 degrees. He or she will show up very, very well on heat-based tracking systems.

I do allow my players to take a mentor spirit for an adept if they choose to. But it wouldn't give them any advantages or disadvantages not described in the original description of the specific mentor spirit. If they want it for roleplaying reasons they can have it.

I don't see any reason to give a adept a mentor spirit that benefits the adept class beyond what's cannon, I don't see a reason to charge regular adepts for mentor spirits that are purely roleplaying...

seems more like powergaming then roleplaying when you go adjusting or creating adept specific mentor spirits.

I don't see any reason to give a adept a mentor spirit that benefits the adept class beyond what's cannon, I don't see a reason to charge regular adepts for mentor spirits that are purely roleplaying...

seems more like powergaming then roleplaying when you go adjusting or creating adept specific mentor spirits.

I think it's a great idea Teapot. Something I'll add into my list of House Rules when my pages are at that point. If you come up with more exact rules for the different elements, I'd not be upset to see them.

Personally though, I think the benefits outweigh the disadvantages in your example. I'd suggest only gaining a +1 Body (for bear) during combat, and no bonus to strength. For the fire, the bonus to reaction is overkill I think. Love the thermo disadvantage though.

Double Eating doesn't seem to fit. I understand where it comes from, but Mystic powers are fueled via astral energy, not food.

Sphynx

Some mentors are fully effective on Adepts, like Rat for instance. Other than that, I see no more reason to make Mentor Modifiers that allow them to apply to an Adept like they do to a magician than I do to make Mentor Spirit Modifiers that allow them to apply to a tradition they aren't normally helpful with.

I wouldn't let a Shaman substitute Beast Spirits for Fire Spirits in the bonuses that Fire Bringer gets, and I wouldn't let an Adept substitute an attribute bonus for Bear's bonus to Healing spells. I would let an Adept produce a new and appropriate Mentor Spirit that added to things she was atually able to do, but I would pattern it off of Rat rather than producing new game mechanics.

If you follow a tradition that doesn't get Air Spirits, such as Vodoun, you just don't have a lot of incentive to take Thunderbird as your Mentor. If you follow a magical path that doesn't cast spells or summon spirits at all, then there will be even more spirits that aren't right for you. My advice is to live with it. There are plenty of Mentor Spirits in the world that are useful to an Adept, the list in the basic book isn't even suggesting that it is comprehensive.

-Frank