It does depend, honestly. Some of them just give a vague sense of fondness as he carries them, though not all of them are particularly intense.

He might note that the puppy's antlers are very similar to the ones Ritsuka had, in the throes of her possession, and that one--along with the Saturn model, and the fluffy round Rider dragon, have a much more immediate and deeper sense of affection when he picks them up. It feels like a hug, the weight of a body leaning fondly against his.

The longer he holds them, the more these feelings will intensify and clarify.