Originally Posted by
Dullahan
Good question. IIRC Shiki has a kind of 'Instinct' (similar to the Servant class ability) which borders on precognition when it comes to combat situations. However, consider this: Canonically, regular (non-BLACKLIGHT) Lio was able to stalk her for years without being spotted or noticed a single time. Take a look at their fight scene the first time they meet in Murder Speculation Part 2 - despite having (presumably) no formal training in knife-fighting, Shirazumi was able to match her on nothing but pure instinct. (Whether or not Shiki was trying to kill him in that scene is irrelevant. The fact is, she was visibly struggling to hold him off.) Now he's got BLACKLIGHT, and is stronger and faster than ever before. He's not quite at Servant level yet, but in terms of purely physical abilities - speed, reflexes, strength, et.c. - he's easily stronger than every 'human' character in the Nasuverse. The only area Shiki still has him beat in is pure skill, which can be rectified easily enough by eating a couple of Kendo masters. Facing either "Katana Shiki" (climax of Paradox Spiral vs. Araya) or "Dead Serious Shiki" (near the end of MS Part 2, where she dismembers Lio in under a second) in Lio's present state could end badly for him, although he's fast enough that he could pull out a win if he struck early and hard enough.
In summary, Lio as he is now probably actually could kill and/or consume Ryougi, although it'd be difficult as hell. Fear of being dotstabbed is a reasonable fear to have when around Ryougi, but it's not the reason why Lio nearly lost it the moment she walked through the door. Anyway, there's no reason Lio could have to think that Ryougi was out to kill him. As far as he's concerned, Ryougi doesn't know he exists. The events of Oblivion Recording haven't happened yet, so Ryougi has no reason to think that anyone other than the Capslockster was responsible for the murders of three years ago. Hell, if he hadn't freaked out, he probably would have just sat at that table, awkwardly making conversation and trying to avoid finishing his breakfast.
It'll probably make more sense next update, when I get around to describing what Lio actually perceived Ryougi as.