In the time it takes Belinda to scan the Doctor, and note the very Doctor-ish aspects of her being, the Doctor decides that somehow - some way - this isn't the Belinda she knows: Not that she could attest to knowing Belinda. She certainly doesn't know what she wants, if being left alone was her primary concern, and now she's most certainly not leaving her alone.
Even in another timeline/reality— whatever, the Doctor is drawn to her, like a magnet. A Belinda magnet. She's about to take the initiative and walk away when Belinda finally says her name.
The absence of emotion in her tone scratches an itch the Doctor didn't know she needed scratched, because she's used to Belinda saying it with such venom. Deserved venom, at that. It's like being bitten by a snake, but only after you jabbed it with a stick for minutes on end. The Doctor really needs to cast the snake similes from her mind, but the Mara really sunk its teeth in.
The sssssnake sssssimiles.
"It..." she looks away, out at the road; at the reflection of the sky in the puddles left by the rain, "...happens more than you'd think?"
Is this really on the way to Belinda's old flat? Even if the Doctor hadn't meant to run into her - as for all she knew, Belinda didn't live there anymore - but maybe subconsciously, she'd brought herself here, roaming Belinda's old stomping ground because she misses her friend and she's too much of a coward to go and say sorry.
She whips her head back around towards Belinda when she accuses her of just that - about to defend herself - but the human woman drops it almost immediately. The furrowed brow she'd sported as she'd been about to refute the claim turns upwards in confusion. Humans can be so erratic.
The next question justifies the look she's giving Belinda. If she wasn't sure that this isn't her Belinda—
No, Belinda wouldn't like being thought about as 'her Belinda.' She tries again:
The next question justifies the look she's giving Belinda. If she wasn't sure that this isn't the Belinda of her reality already, she is now. Her lips fall apart, just for a moment, shaping the beginnings of a word. Truthfully, she doesn't know how to answer that.
She isn't the last of her kind. She knows there are others out there. For one, the Master is a golden tooth in her TARDIS currently. But for simplicity's sake, she says it, her eyes turning downwards and gulches digging in on either end of her lips as she frowns.
"Last of my kind," she says it shamefully.