That was a very large rat. The constantly moving, skittering heat signatures at the edge of Tony's awareness suddenly bloomed into a proximity alert, its sensitivity heightened instinctively with the cautious tension between his shoulders and his shallow, attentive breathing. The steady ringing of metal on concrete came to an abrupt halt, the last echo of it absorbed into the fall of dark water, and Tony watched the web of the map sketched in front of his eyes off of the reverb come into shape. The anomaly in the architectural grid ahead of him, shifting subtly with a sway with the hollow wind that flowed through these passages, was far too big to be a naturally occurring sewer vermin, and definitely far too stuck-to-the-ceiling to be be a naturally occurring sewer rat. Tony's instinct, and for this he would be cursing himself as he sweated it out in an upcoming nightmare, was 'gamma irradiated cockroach', which was almost enough to make him turn and retch if he could bring himself to take his eyes off of it then. Instead, he carefully raised his glowing hands, the high whine of the repulsor charge blending into the murmur of running water, and shuffled slowly forward on his toes as he invited the mystery creature into his monologue; "If you're a cockroach, I swear to god--we can end this peacefully, if you just stay right there and I'll hightail it back the other way, what do you say?" It was okay, no one had to know about that. Besides, he didn't know a lot of people willing to face a HulkRoach in the dark without a lot of forewarning either, he would bet.