A Bone Suckler will idly wander around on it's own. When Aya gets close enough, it will head right for her with the intention of blowing itself up to do as much damage as possible. When one gets close enough, it will stop moving, curl up and build up it's detonation before finally exploding. This attack has a considerable radius, so try to hit it from as far away as possible or try to escape from the suckler before it explodes if the player is too close.
The explosive damage this creature inflicts is not exclusive to Aya; other Bone Sucklers and NMCs will take 60-71 damage (on Normal Mode, less on higher difficulties) per explosion. Try to take advantage of this by shooting Bone Sucklers during the rare few times they are nearby other creatures.
After a while of idle movement / chasing Aya, it will eventually stop chasing her and fall asleep for a while.
It is unknown if the Bone Suckler or the Blood Suckler would develop into the Mind Suckler.
There are three unused enemy encounters in Akropolis Tower and two more in Dryfield that include Bone Sucklers.