Around these parts, we love all our Doctors equally, like children or mimosa add-ins (just kidding, grapefruit is clearly superior), but we will always have a special spot in our hearts for David Tennant's 10th Doctor (the grapefruit mimosa of Doctors). His frown, his hearts, his shoes, we love our fluffy-haired boy. But one episode and one very helpful companion reminded us that the man loves two things: blondes, and an ENTRANCE.
In the Doctor Who episode "Girl in the Fireplace," the Doctor is ready to give it all up for Sophia Myles' Madame de Pompadour (who he clearly preferred to Rose, effectively smashing your favorite ship like a well-dressed iceberg) and when the big moment arrives to save her from the scary clock fancymen, he does so with the help of his new friend Arthur. Arthur is a horse by the way. (Good name for a horse.)
Arthur follows the Doctor around (I would too, Artie, I would too). They become very tight very quickly (he seems to also prefer this horse to Rose, look, Steven Moffat clearly did not share the Rose/10 OTP feels) and when things break bad, the Doctor breaks EVERYTHING, bursting through the mirror that connects pre-Revolutionary France to the TARDIS in the 10-est way possible: with a lot of drama...
...and a LOT of flirt.
He should have kept the horse. People come and go but Arthur would have stayed (and neighed).