Tarn peeks into the building, hesitant to blindly go into a confined space with this stranger; especially with her to his back. He look at Zarya with suspicion for a few moments before taking the risk. He's sure that if it's a trap, he'll spot it before any harm can be done.

Besides, the moment he sees that roaring fire in the hearth, he can't bear to stay in the cold for a moment longer, even if it would be wise to have Zarya go first. He makes a bee-line for the glow of the fire, shrugging off his wet jacket the moment that he reaches it's warmth.

"You have my thanks. Perhaps I will walk away from this learning experience with all of my limbs still attached and no permanent damage."
The barest hint of a smile tilts his scared lips as he melts into the comfortable heat.