Archer returned to the hotel room directly from the battlefield. Being followed didn't concern him, he couldn't sense another servant's presence so only Assassin could possibly be tailing him, and if that was the case then there are worse things to have happen. If they were to set a trap for Assassin, they'd need to lure him with some enticing bait anyway.
Andrew welcomed him back upon his arrival. "Archer, you fought magnificently tonight! I was in awe just watching the two of you go at it. I'd heard servants were powerful beings, but that doesn't fully prepare you for the spectacle of a battle between servants" he said enthusiastically. Andrew continued when he saw Archer take a seat with a tired sigh "how are you feeling Archer? It looked like you were throwing out some pretty impressive attacks. I think I counted three astras all up."
"That's right" replied Archer "Lancer withstood two of my more minor astras, and survived with some injuries. The third I needed to use to secure an easy getaway. Depending on the power of the second servant I might have been able to kill them both there, but there's no point in risking that so early in the war. I've still got enough prana to use two or three more of my smaller astras though I do feel slightly fatigued after that ordeal, I've never had to use three in one fight before. From that perspective it looks like this grail war will be as entertaining as I'd hoped."
"Okay, get some rest Archer" said Andrew. "I'll do the same and we'll go over the implications of tonight's clash tomorrow morning. Feel free to replenish your prana from my own stocks while I'm sleeping" and so saying Andrew Whitcombe, master of Archer, heads to bed.