At the moment, Isaiah wasn't concerned with the demon. It was already dead - gruesomely, and he could still feel the repulsion churning in his stomach from being close the corpse - and his only thoughts now were of Raina and making sure she was okay. The hand she laid on his cheek was more reassuring than Raina probably realized; Isaiah took it as a sign that she wasn't completely in shock.
If the interior of her house was trashed, Isaiah figured the backyard, where the actual fight had happened, would be too. In the back of his mind, he knew that fact would be traumatic for her, being an Earth elemental. But the garden could be fixed, he could help her mend the hole in the fence, they could put everything back together. He just had to take care of her first.
When she spoke, however, the words that came out weren't English and Isaiah's brow furrowed, his head tilting to the side a little, his brain unable to translate that. It took Oma's explanation afterward for some of it sink in. "This is from the demon?" Of course it was, Captain Obvious. It was a side effect he'd never thought of before, considered that the demon that attacked him a few weeks earlier hadn't done this to him. If even Oma couldn't understand her thoughts, this spoke of serious trauma.
The fact that a vampire had been here too, but was gone now - Isaiah would have been able to smell him, he thought, even over the stench of the demon - was something he'd ask Raina about later. For the moment, he chose to believe that the vampire had at least helped take out the demon, and saved Raina's life in the process. His brain, at the moment, was trying to figure out how he could best help her, and he just kept coming back to one thought - his mother, the white witch. Maybe Adriana would know what to do. "You can understand me, though, right?"