For a DH game I once had a little girl trail behind the team. I gave them a clearly defined reason why to keep her: she knew the exact whereabouts of the cult they had been hunting down for months, but she was so traumatized she couldn't say it. Therefore they had to take her for investigation.
She had been a prisoner of the cult for the few years of her life, and it left her a wreck. Whatever term of "cute" you could apply to her horrilbly beaten form was only by the sheer pathetic stance and gait she had mixed with soft peaceful mumbling.
Unfortunately for the team, this girl was quite a handful. Much like the savant in Eisenhorn, she had an OCD obsession with collecting as much data as she could, and would constantly wander off to inspect the serial number of heating pipes and prediciting their path and average internal pressure. Often times she would get herself in dangerous situations, such as one time when she opened the door to a moving snow-skiff (she was determining the handle's maximum degree of movement), or when she stumbles into bandit camps.
The girl lasted about 5 sessions, and over that time the team actually bonded with her, in a sense. They would actively protect her, constantly monitor, even keep watch specificly on her as she slept. Most characters would say this was strictly professional, but the party's adept was fond of her curiosity, reminded him of himself.
In the end she was taken into an Inquisitorial Outpost on a local moon, where visiting Inquisitor Darrus Ingramm performed a cortex planing, resulting in over sixty thousand tissue thin slices of her brain. The Inquisition was able to successfully locate the cult from this autopsy.
The party was rewarded and given citations.
The adept doesn't wear his, he keeps it on top of thee girl's dataslate, which he keeps amongst his own. Sedimental reasons.