It's a simple companion in the style of Fenrir the wolf.
(If you've used that one, Kajsa is a little stronger than Fenrir but with a little less HP)
Orders include Follow, Stay and Go Home. You can define a new "Home" Location.
There is a summon power, and quest marker to help you find her.
She has catch up teleporting in case she falls behind when following.
Kajsa is Essential, so she can't die but can be knocked out.
She levels with you.
She sneaks when you sneak.
She has water walking/water breathing.
Since she's a troll she regenerates health slowly.
She regenerates damaged stats.
When you activate the mod you will be given the summon power.
You must use this spell to call her into the gameworld the first time.