That was definitely Severus Snape. If the look and sound of him wasn't enough, the sharpness of his tongue filled in the rest, suitably causing Jonathan's eyes to go wide with intimidation as he took a slight step back, worried that the wizard might actually strike him down or something. It wasn't like he was a Hogwarts student, so there wasn't anything stopping him! And sure, Jonathan had dabbled in magic, but his specialty was in long rituals and glamours, nothing offensive or defensive! And not against Severus Snape.
Anna's glare towards him had Jonathan curious, but there was so much rushing through his mind right now that he didn't ask. Maybe everything would be revealed with a bit of time. Just… he needed to keep breathing, relax, and keep his cool. Yeah, he could totally do that! He'd kept his cool well enough with Willow went all crazy on the dark magic, he could handle being suddenly displaced to a reality where fictional characters existed in t he flesh.
And okay, as terrifying as Snape was, it was so cool that he was there.
Nodding at Anna's statement on it not being important, accepting that as he was, Jonathan continued, elaborating on where he was before suddenly showing up out of the blue. "Yeah, we'd just uncovered the Seal of Danzalthar on Sunnydale's Hellmouth under the new high school. We'd been having these nightmares in Mexico, something telling us desde debajo de lo devora. So... we knew it was serious, came back, found the seal and were on our way back to tell Buffy and her gang about it."
Folding his arms and shifting uncomfortably, he frowned as he added, "We weren't exactly on good terms, but it was important for them to know. Buffy's the Slayer, so she could use what we knew to fix it. We were about to leave the basement when I just... showed up here."
Jonathan's eyes grew wide as he suddenly realised. "Oh my god! Andrew's alone back there! In that creepy, awful place... I have to go back!"