Mole rats are mutated rodents that are much larger than their pre-War ancestors. They have survived as a species by burrowing underground where the soil protected them from direct nuclear explosions. However, they still were greatly mutated by the subsequent radioactive fallout, increasing their size as well as their viciousness. A few people in the wastes have even been known to train them and keep them as pets.
Mole rats are generally found in packs of three to four, but are occasionally encountered in pairs, or by themselves. They are often witnessed standing on their hind legs and sniffing the air, allowing them to smell any approaching predators. They occasionally scratch at the ground, attempting to dig a burrow.
Mole rats are very aggressive, but may retreat if severely outmatched. They fight for their food by biting at their prey with their large incisors. When attacking, mole rats charge towards their opponents and have a long melee range, with the ability to lunge several feet towards their opponent.
Mole rats are usually hostile unless the Lone Wanderer has the Animal Friend perk; they will fight alongside the Lone Wanderer in battle if they have the second rank of the Animal Friend perk.
Moira Brown noted in her computer terminal that mole rats can be domesticated, but only after de-clawing, de-teething, and a lobotomy, although Pumpkin seems to disprove this (this could be just an untested hypothesis of Moira's and she had not yet tried it).