[As he moved down the tree he got about mid-way before his grip with his feet and arms started to slip, and he clung to the trunk to no avail, turning in such a way that as he fell he happened to descend face-first so that as he flailed comically for a moment he landed right on top of Ivan in an awkward position so that his mouth was incidentally covering his.

All in all it was a terrible accident waiting to happen, the tangle of limbs and muffled "oof" of having someone knock you down no doubt bad enough. The surprise kiss that was entirely not his fault just took the cake, however. Well, they didn't call it leaving someone breathless for nothing!]