When the man in the boiler suit stopped talking, the woman in the leather jacket would take up the thread and continue it. When the woman in the leather jacket stopped talking, the man in the boiler suit would start again.
Tilly sat in her armchair, eyes moving to one speaker and then the other, not speaking even to ask a question. The only time the two Others saw any emotion on her face was when they explained their theory that humans and hostiles were possibly related, given how they both consumed carbon compounds without heed to sustainability.
Eventually they finished, and Tilly got up. "I'm starving," she said. "I'm making tea and a sandwich. Do you two want anything?"
"We can't..." the woman with the leather jacket started.
"All right, all right," said Tilly. "But I'm going to." She headed into the kitchen, put the kettle on, and used the excuse of making the sandwich and boiling the water to gather some thoughts. She tried to remember every interaction she'd ever had with them. Or, at least, that had seemed to be them.
She sliced up some cheese to make the sandwich with and frowned. Ethics and historical precedence were her strong suits. Neither was going to work here.
"Quantum physics," she announced, carrying a tray with the tea and food on it back to the living room.
The man and woman had been conversing in low voices with each other, casting nervous glances at the door out of the apartment. "Eh? What's that?" said the man in the boiler suit.
"Quantum physics," said Tilly. "There's a theory in quantum physics that once you observe something, you change it. Only applies to the particle level, but scientists have to take a similar outlook into account when they are studying macro objects, like trees or oceans. Or animals."
The woman flinched and shot a look at the man, who said slowly, "We have similar restrictions on our research..."
"Really?" said Tilly. "You could have fooled me, seeing as how I first encountered you when I was six years old." She added milk to her tea. "I've been able to spot you regularly ever since then. You were an administrator at my faculty in university. You were even the bus driver on the Greyhound we took from Montreal to Toronto." She peered at the woman in the leather jacket. "You might have even been the girlfriend of our contact at the cherry orchard co-op."
The woman in the leather jacket shrugged. "I was trying to compare human sexuality to the cherry trees. Sexual reproduction isn't as common in this galaxy as you might think."
"Fascinating," said Tilly, washing down a bit of sandwich with some tea. "The point is, from the point of view of this particular test subject, you haven't been very good scientists. Not by Earth standards, which I suspect are a lot more lax than where-ever you lot are from."
The woman and the man exchanged glances.
"And now," said Tilly, taking another sip of tea to extend the pause, "You're asking your test subject for help. All right, I'll draw on whatever vestigial hunter-gatherer instincts I have and ask you: why should I? Besides scaring me half to death, which was largely your fault for warning me about them — interference on your part again, see — what harm have the hostiles done me?"
"They've killed at least six of your kind," said the woman. "Those bodies they inhabit — they're not alive anymore."
Tilly set down the sandwich half she was holding and forced herself to swallow. "I was wondering about that when they talked to me at the subway station."
The man in the boiler suit startled. "What did they talk to you about?"
"When that homeless man killed himself, said he'd found the door in the ground," said Tilly. "They wanted to know where the door in the sky was. You keep putting it in the wrong neighbourhood, by the way."
The room suddenly smelled of oranges and lilacs, and Tilly could have sworn that for a moment, the woman in the leather jacket turned green. Noises came out of her that Tilly would never have dreamt were possible for a human body to make, but they seemed intelligible to the man in the boiler suit, who paled.
"The door in the sky is for you to travel back to our world with us, safely," said the woman in the leather jacket. "And it's completely against protocol to set it up without determining timing, location, and willingness of the subject beforehand."
"Well, someone's put it up about twice, right altitude, but in completely the wrong neighbourhood," said Tilly. "I've seen it, and my grand-daughter has seen it twice."
Someone thumped at Tilly's door, and all three beings in the living room jumped. "Mrs. Zondernaam?" said a voice with a slight Spanish accent. "I can hear voices. I know you're in there. You left your garbage in the garbage room again. You're supposed to put it down the chute."
"Nonsense," called Tilly. "I always put it down the chute."
"What are you doing?" hissed the woman in the leather jacket. "She's one of them. What did we just tell you?"
"She can hear us talking," whispered Tilly. "I've heard plenty in that corridor. You asked me to, remember?"
"Mrs. Zondernaam, open the door."
"Certainly not," said Tilly. "If you have a complaint about me, we can mediate with the supervisor. You have no reason to accuse me."
"Have it your way," said the voice in the corridor. There was a light thump against the bottom of the door.
The man leapt out of his seat and ran towards the door, while the woman stood up and started fishing around in her coat pocket.
"Hurry!" shouted the man. Tilly stood herself and turned to see what they were looking at.
A white light was slowly brightening the crack under the door.