(So I'll try and be as gender neutral as I can, also I wouldn't really be writing the relationship between the reader and The Doctor as obviously romantic, also I'm not going to say which Doctor so you can imagine most of it how ever you want.)
You stared at him, you were on the verge of crying. "No, no please." All he did was give you a sad smile.
"I have to."
"Doctor please." You reached out for him, and he hugged you. You leaned into his chest. "Doctor, please you can't." As you spoke a sob broke your voice.
"I have to." And his voice broke too, he didn't want you to leave, you didn't want to leave, but you both knew it had to happen.
"N-no." You pulled back, enough to look up at him, pleading with him. All he could do was give you sad eyes, it couldn't be prevented and you knew that.
"I have-" you shook your head, your eyes closeing while you did.
"Don't, I know." You opened your eyes, and looked at him again, you knew you should just let him send you away, you shouldn't keep dragging it out and hurting him like this. "It-it's just... there's so much more to, to see. I-I wasn't supposed to leave you... not now. I'm-I'm sorry." Your voice broke, again and you could feel another wave of tears ripping through you, you pulled yourself into The Doctor again. "O-okay," you said finally, the hardest and simplest word you had ever said. "But, but you make it count." You pulled back and looked at him. You place your hands on eaither side of his face, makeing sure he looked at nothing but you. "You make it count you got it? You save humanity again okay? And make damn sure you do it any time we need you to okay?"
He nodded, holding back his own tears. "I will, I promise I will." You gave him the best smile you could muster at the time.
You let go of his face, and wrapped your arms around him, hugging yourself to him. "You are the best man I've ever met."
You heard him take a deep breath, probably prepareing to say what ever sentiment he was hanging on to. "No- you don't have to. I don't want you to. I just wanted you to know that." You gave him one more squeeze, you held on to him as tight as you could one more time, and it was the last time. You pulled away and looked at him, every part of you wanted to smile at him, a real smile like the one you gave him the first time you entered the TARDIS.
***
The door to the blue box opened infornt of you, and The Doctor peered out of it, grinning. You raised an eyebrow at him "Well? Can I come in now?" He nodded his wide smile still holding as he looked at you, and opened the door all the way, stepping back so you could walk past him.
You walked into the box with a expression on your face which showed your low expectations, that quickly changed. Your eyes widened as you took in the inside of the TARDIS, you could feel your excitement and wonder building, it was...
You had to make sure, and you pushed past Tkhe Doctor again, running out to look at the outside of the TARDIS. you started to run your hand along the outside walls of the TARDIS, yep just as you thought, you took very little time in getting all the way around all four walls.
You found the door again and ran back into the TARDIS. The Doctor was leaned against the console of the TARDIS, he smiled at you with an expectant look.
"Well?" Your excitement could only be expressed with one statement.
"It's round on the inside!" The Doctor looked confused, but only slightly, maybe he'd been expecting you to say something different.
"Well, that's a new one... But yes, it is round."
You grinned at him, a true expression of your happiness.