Koschei is stripped of all armor at once, perhaps all the more endeared that his Theta speaks with such evident and breathless fear. For it’s known, it’s very much known, how hard it is, the act of speaking those three words.
He finds himself uncommonly shy, in that moment, eyes downcast.
“You didn’t have to say it,” he attempts to reassure, leaning greedily into
the petting of his face.Fingers smooth down nonexistent wrinkles on the Doctor’s shirt.
“Really. As you say, I know. I do.”
The remark of vulgarity earns a positively fanged grin.
“It’s bloody well fun, from time to time, to exact a role reversal, eh?”
Hands reach up to ruffle brown bangs into further disarray, affectionate and just slightly needy, always parched for more of his best friend’s follies, always entirely besotted at the exact same time as he can cut through every illusion and see the little boy he fell in love with eons ago. It’s a marvelous double-think, to be able to believe ardently in the persona, and also know the truth beneath it: to know this mysterious wanderer through and through, and relish him all the more.
“In any case, I’ll never forget hearing you say those words.”
Theta feels the shift in atmosphere and he, too, sheds the armor that surrounds him. Mentally, physically, any protective covering that would shield him from something unsavory or potentially hurtful falls away and he, like his Koschei, finds himself entirely enamored. The benevolence and vulnerability surrounding this moment lets him know that he’s chosen the proper time to allow himself to temporarily overcome his deeply rooted fear of those three, simple words that in reality aren’t simple at all. They are complex, as molecular compounds and genetic codes are complex. They mean everything.
Fingertips brush along the other Time Lord’s cheekbone and temple, jawline and forehead, palm never losing the skin-to-skin contact as his hand is sought after by his beloved.
“I don’t say it because I feel the need to reinforce or reassure you of it. It’s one of the few Universal constants that remains unwavering. I say it because I want to. Because.. I feel it, and even though you know, sometimes it needs saying, if not for your sake then for my own.”
That fanged grin is returned to him with Theta’s own mischievous smile, that of a school boy who’s found the most brilliant way to avoid doing his homework while still receiving excellent marks besides. A resurgence to a time and place long past, yet still present. He lets out a breathy half-chuckle through his nose as his hair is ruffled- perhaps one of his favorite signs of affection, in this or any regeneration, the hair touching -and the accompanying eyebrow lift is able to be felt against the other’s forehead.
“You’d be surprised how well I can play at role-reversal. Might also be surprised at the vulgarities I’m capable of, given the circumstances call for it. Been known to thoroughly castigate a toaster or two in my time.”
The mischievous smile softens into one of devotion and reverence, then.
“Just as I’ll never forget nor tire of hearing you say those words to me. I may not say it often, and you may know it regardless of that fact, but- well, I’d like to be able to say it without hesitation. I want to say it as loudly and as often as possible, and they say the best way to overcome something that causes trepidation is to face it. So…”
Another pause, another breathless and quivering confession.
“…I love you.”
There, he thinks, he will stop. Twice in less than five minutes is near a record for him, and he doesn’t know if he can manage a third without becoming faint. At least not aloud. For him, silently speaking the words his lips don’t wish to form within the realm of their telepathic frequencies has always come much easier.

What a courageous declaration this is. His hearts swell with pride.
“I’m sorry I ever called you a coward, my love.”
The Master’s features are so soft and indulgent as the Doctor speaks to him of hope and expectation. The Doctor savors that he has chosen the “right time,” but really, this proclamation is eternally welcome.
“I forget that I am a thing made to destroy, when you say it. I forget
anything but what you hope to see in me, vain and sentimental though
it may be. It has always been my weakness, this hunger to please and
impress you.”
Fingers drop from the Doctor’s hairline and explore the terrain of his face. They trace rakish eyebrows and the bumpy bridge of a sharp nose. They explore cheekbones and epidermis.
“Will you take me on a new adventure, my Theta? Will you pick us a
planet and grab my hand and tell me to run with you? Show me you
love me: you can have a rest from the Hard Thing of Telling
now. Only take me along with you, and I’ll always know.”