I was determined that if the horse would but remain stationary I should step up to him, speak to him, give him a quick pat on the neck, gather the reins in my hand, place my foot swiftly in the stirrup, take a good hop, and be on his back before any one had time to notice.
Dr.Bell, however, caused me to alter these plans; for though he had stood docile as a dog while the sisters patted him, his manner underwent a change on sight of me.

I do not think this change was caused by any personal dislike for me.

I believe he would have done the same had any stranger appeared before him in riding boots.

The trouble was, probably, that he had expected to be ridden by one of the young ladies, and was shocked by the abrupt discovery that a total stranger was to ride him.
This is merely my surmise.

I do not claim deep understanding of the mental workings of any horse, for there is no logic about them or their performances.