An impossible promise, but Wysteria has made a habit of asking too much. So far, Ellis has found a way to avoid disappointing her. It tends to be easier, when she's asked that he carry this or fetch that or hold such and such a thing in place. Even when she's after a particular sample or alchemical compound, those are easier to mitigate than the prospect of being something in neighboring extraordinarily well.

Straightening, Ellis' expression creases into a subdued, fond smile. No promise is forthcoming, though he reaches to interrupt her ministrations. A regrettable turn of events for Ruadh, perhaps, but that prospect isn't enough to keep Ellis from catching up her hand in his own.

Certainly, he could have made the promise. How could it be verified one way or another? But Ellis imparts something else, instead.

"He has a keen sense of smell," comes with a tip of his head downwards, towards the seated mabari. Still panting, hopefully attentive to the two of them. "If Ruadh tells you to go, heed him. Aye?"