Once merged with a character, Avatars are sterile which means they cannot have children. An avatar may be an individual, swarms, packs, or groups. Until they are above tier-1 they cannot split into different movement groups.
Memories of avatars are combined with the character to form the character. This is like body snatchers where the memories take over the mind of the avatar. Most creatures in this world do not understand the idea of soul possession. Those that do consider it a great honor to be invaded by the memories of a character. The character will remember the host memories including the instinctual ability to move and eat in the avatar. Characters must learn how to use their new avatars; this is not always easy.
The process of merging is not always smooth, and it can take time for the memories to fully integrate with the avatar. Sometimes the memories can clash with the existing personality of the avatar, causing confusion and disorientation. Other times, the memories can amplify and enhance the existing traits and skills of the avatar, leading to incredible feats of strength and prowess.
Two characters with a single avatar each by agreement may merge to form a single character with two avatars at tier 2. All memories are merged if this happens. A player may only use one character without GM approval. A player operating more than one character is not recommended. A character having more than one avatar is encouraged above tier 1.
Memories cannot separate from an avatar unless the avatar dies. After death of the avatar their memories stay with the character.
Not all avatars have the same number of slots. All avatars have at least 14 slots, some may have as many as 20. Where the slots are, and the number of slots depends upon the type of avatar and how powerful they are. Some items (like a belt, sheath, or backpack) may add specialized slots.
Avatars with characters of tier-2 and above can share their thoughts and senses through their memories. This does not require either avatar to go blind or deaf. Both can see what the other sees and hears, but this starts to get dim after 20 feet. After 100 feet they can only tell the direction to the other avatar. Some items may increase this distance.
Avatars with characters of tier-4 and above no longer have distance restrictions of sharing their thoughts and senses within a single plane of existence.
Avatars with characters of tier-5 no longer have restrictions of sharing their thoughts and senses across all planes of existence.