The soul is held down in the physical plane by the brain. As long
as the brain isn't destroyed, there is some possibility of a magus
recovering.
A soul, a part of the concept that is the astral plane, is the
memory body, or rather the record(information) that the world keeps of
a person. - Fate/stay night - Zouken.
A soul is comprised of spirit particles. - Tsukihime (or Melty
Blood) - Have yet to see actual proof of this outside of net yougoshu.
The spirit particles of a soul, once "destroyed", disperse and
return to the root to await conversion in their next form. - Tsukihime
- Same as above.
The "ghosts" that most normal people think of are just the leftover
fragments of the mind/soul that the environment/world maintains. -
Rakkyo
A soul, as opposed to one with a materialized mental body (ie Servants), normally has no alignment on its own. - Fate/stay night
Information of the soul can "decay" over time. - Fate/stay night - Zouken
The soul is the sole indestructible and eternal thing in the
material plane. However, it can't exist as an independent object and
once anchored to a body, it can last only as long as the lifespan of
that body.
Prolonging of the soul is possible through the prolonging of the
flesh by making it undead. However, the soul itself still decays. -
Tsukihime
Souls of the great heroes are removed from the normal cycle of transmigration and stored in a throne. - Fate/stay night
The requirements to be a heroic spirit is not so much the degree of
the deeds accomplished, but the fact that absolute destiny/fate had
been altered. - Fate/stay night
Heroic Spirits don't have "memories" because they're already a completed past record. - Fate/stay night - Kotomine
The Holy Grail is able to shape that past record into something
that resembles the original. However, it still is considered a part of
the past not a part of the present. - Fate/stay night - Heaven's Feel
"Real" is considered anything that does the same exact thing as the "original". - Rakkyo
Memories from the Servants aren't carried over to the main body. - Fate/stay night and /hollow ataraxia
Memories consist of things that a person directly experienced. A record is the information that the world records. - Rakkyo
A record is ultimately only pure information. For example,
knowledge that a series of components and other facial attributes =
person A instead of actual recognition. Person A is still a stranger. -
Rakkyo - Kurokiri Satsuki
The soul is shaped by the body. Without a body, the consciousness
of the soul is changed into something else that probably lacks any kind
of awareness similar to a human being. - Rakkyo
A body that is exactly the same can reproduce the soul of a dead
person given that the necessary mental information is transferred. -
Rakkyo - Touko
A counter-force sends out power to people and/or possesses a person
(when no one is observing) in order to suppress any problems. - Rakkyo
A dispatched heroic spirit may gain experience and learn many
things, however, what is gained is never retained. - Fate/stay night
The soul of a Heroic Spirit is inclined to return where it originated from. - Fate/stay night
It is possible for the status if not the memory and skills of the
Heroic Spirit to change depending on what happens when he/she is
incarnated as a Servant (mutation into a gorgon by Medusa, fame gained
by someone that is a relative unknown like a Hassan). - Fate/stay night
The only thing that is transferred is the record/soul of what
happens. That information had already been there since the beginning
however. - Fate/stay night - Archer
"Reincarnation" has the flaw of corrupting the original personality
of the soul. The base personality for that incarnation is derived from
its current incarnation. - Tsukihime (Roa)
A soul is only regarded as a vessel. The mental body is a product of the soul and the physical body. (Rakkyo + Tsukihime)