Shirou could only feel himself tense up as the spiral-headed thing spoke to everyone like they were on familiar terms. He couldn't really speak for anyone else, but Shirou didn't get the feeling that anyone in this room had even half a clue what this guy was. However, the way he spoke to Shirou put him on guard a little.

For a start, this thing knew his name, and of the grail war. Amongst magi, he understood that the war wasn't exactly secret, but beyond that, how many could know of it? More specifically, of Shirou himself? He may have survived the war, but ultimately, the 'winner' would be Rin, wouldn't it? Saber was contracted to the twintailed girl by the war's end, and still was, in fact.

Perhaps more worrying for the young student, was how Swirl implied knowledge not only of Saber's true identity, but... Archer's, too? Shirou may have misunderstood what exactly the creature meant in regards to the 'time' he came from, but it didn't really change the fact he knew way too many details for Shirou's liking. It was hard to trust a faceless creature that pulled several strangers into a weird room without warning and put on such a friendly show.

Still... Shirou couldn't sense anything malevolent about him. He wasn't going to lower his guard just yet, but he didn't get a sense of impending danger, and without Saber's protection, he really couldn't afford to make any stupid mistakes. For now, he'd just need to hear this guy out.

...It annoyed Shirou that he couldn't help agreeing Saber would have been the better pick, however.