Years of experience allowed Severus to force his tumultuous feelings under control. And they were tumultuous. He'd never really been able to wrangle them properly when it came to Lily. He had loved her, still did love her in some way he couldn't define... or wasn't willing to define... or wasn't able to define... and would probably always love her. His patronus was proof of that. He knew there was probably some trite line about first love being eternal that Albus - older Albus - might well have thrown in at this point, just to annoy him, had he been here.
But he also knew that his love for her back then had not been healthy. Not for her and definitely not for him. He had never had a healthy example of love to learn from. His parents, he knew, had loved each other but they'd also spent their time tearing each other apart - his father overtly and loudly and violently and his mother with all the Slytherin cunning she had possessed... which had been a lot. There had been a lot of reasons why he'd spent a lot of time out of the house. Too much time really, even for the Muggle standards of the 60s. Though it had been those same standards that had ensured no one had ever called the police. It just wasn't done to interfere with other people's private affairs.
"Lily," he said as he mercilessly shoved all of that back down into the little mental box he usually kept all things 'Lily' in. "It is... good to see you." And it was. She hadn't changed from the last time he'd caught a glimpse of her. Obviously. "Ah yes, I had noticed you were working with the new Department of Mysteries."
He opened his mouth to say something else, hopefully something less stilted, but a low rustle from behind him had him skipping forward quickly then turning and slashing down with his wand with a quick wordless spell. The two vines from the nearest Venomous Tentacula that had been slinking quietly towards him quickly slithered backwards and the plant itself rustled ominously.