A/N: Olfactus was, in my opinion, one of the three worst episodes of Eleventh Hour. I've wanted to (eventually) write a missing scene for all of the episodes but this one irritated me. I couldn't see where any Rachel/Jacob interaction would add to or improve it. Then Felix piped up and an idea was born.

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Felix Lee looked up from his cell phone, "Agent Young's about twenty blocks from here, should we take a taxi or the subway or something?"

Jacob Hood jumped down from the runway, "Nah, let's walk." He looked around at the wreck of the fashion show venue, the paramedics still treating injured spectators and models, the police still trying to make sense of the sudden eruption of violence. He shook his head slightly, "We could use the fresh air."

He led Felix from the tent, but once they reached the street, Jacob pulled up, looking around puzzled. Felix hid a grin, for a genius the Doc wasn't too hot on practicalities. He consulted the map app on his phone. "This way Doc."

Both men were lost in thought for the first few blocks, then Felix broke the silence. "Man, it's hard to believe six people are dead 'cause that jerk Boyle was pissed about being ripped off by his boss."

"It's not that surprising." Jacob replied. He interrupted Felix's indignant response. "I'm not defending him but his complaint isn't uncommon. Research is expensive, researchers often give up the rights in their intellectual property, work, to their employers. For most people, they're willing to pay that cost to get the work funded. All the same," he shrugged, "after a while it can be galling seeing someone else get rich off your ideas."

Felix raised an eyebrow, "Really? I thought that's how those bazillionaires made their money, inventing stuff. I mean, look at Bill Gates and Steve Jobs."

Jacob gave a small huff of laughter, "they got rich because they were practically broke, working in their garages when they made their breakthroughs. Then they went out and got financing to build their companies; they never lost control of their work. Success stories like theirs are few and far between."

"Huh," Felix nodded his head in understanding. This was one of the reasons he liked this gig, he learned something new every day. The two men lapsed into silence once more.

After another block Felix spoke up again. "Ya know, Doc, there's something I don't understand." At Hood's look of inquiry he plowed on. "People are always talking about two people having chemistry, even Agent Young was talking about it. So, those neuro-what-cha-ma-call-ems? And the premones?"

Jacob interrupted with a smile, "You mean the neurotransmitters and the pheromones?"

"Yeah, them, how do they really work? The stuff Boyle invented was supposed to be a 'super love potion,' Remember those letters we read? About people feeling, uh, aroused? I mean, even when Boyle sprayed perfume all over the place, not all the guys there tried to attack the models."

Jacob took a deep breath, 'Crap, am I really going to have to give Felix the sex talk?' "Uh, well, it's not that simple. I mean . . ." He took another deep breath. "Human sexuality is complicated." He cocked his head, "it's not very genteel, but sexologists . . . ."

Felix snickered, "sexologists?"

Jacob frowned, "yes, doctors who study human sexual response. They say that when it comes to sex what's between your ears is more important than what's between your legs."

Felix burst out laughing, "I never heard that before."

Jacob waited until Felix had himself under control. "Human response to sexual stimuli is strongly influenced by your brain. That's the real chemistry involved. In this case, the concentrated pheromones in the perfume acted on the arousal centers of the brain and the neurotransmitter Boyle added stimulated the amygdala, which caused the aggression."

"I get that, but like I said, not all the guys there were attacking the models, hell, some of them were hiding, trying to get out of there. Are those pheromones that picky?" He looked sideway at the Doc, "I mean, I didn't . . . ya know . . . feel anything . . . . Did you?"

"That's part of what I meant when I said human sexuality is complicated." His lips twitched, "when we were in that tent, what was going through your mind, what were you thinking about?"

"Uh, well, to be honest Doc, I was kinda in a panic. Worried about what might happen to all those people if the antidote didn't work." He didn't add, 'Worried that Agent Young would kick my ass if anything happened to you.'

Jacob nodded, "Feelings that are controlled by the hypothalamus, which can over-ride the amygdala." At Felix's quizzical look he elaborated, "The thalamus, hypothalamus are the parts of the brain that control higher level activity; you were concentrating on doing your job, plus you had a lot of adrenaline in your system." He shrugged, "you were distracted. People don't enjoy, think about sex, when they're distracted."

Felix chuckled and hummed a few bars of the old song, "So I wasn't 'in the mood for love', huh Doc."

Jacob's lips twitched. "Partially, plus humans are much more dependent upon visual cues in socio-sexual behaviors than on smell. In other words, pheromones may pique your interest, but if you don't find the woman visually appealing you most likely won't have much of a physical reaction." He lifted an eyebrow, "That's the so-called chemistry people talk about. Maybe a hint of pheromones but more importantly an attraction based on physical attributes.

In your case, aside from the adrenaline, you may not have felt any arousal simply due to the fact you didn't find those models attractive." He shuddered. "Frankly I thought they all looked as if they could use a good meal."

"You're right 'bout that Doc, I can't stand a skinny-Minnie," he winked "I like a woman with some junk in the trunk."

Felix felt the question slide up his throat 'So Doc, what kind of woman gets your motor running?' and swallowed it down again. Besides, he had a sneaky feeling he already knew the answer.

He got his confirmation when Doctor Hood spotted Agent Young at the next block and a look of relief crossed his face.

"Look there's Rachel." With a faint smile on his face Jacob strode off leaving Felix thoughtfully trailing after him.