[Sherlock blinks a few times rapidly, looking at John for a few seconds. The odd bit of tender emotion and physical impulse is enough to catch him off-guard.]

Just stay with me, John. Let's get you upstairs.

[He wraps an arm around John's waist to help support him. Between that and the handrail, it shouldn't be too much for them.]

I'm going to need you to walk me through some of this, alright?