You give it back to her

(all credit to Dreamer44 for his passages on Alpha Essence, copied here)

You weren't sure if Crystal had been conned or not, but this seemed too good to be true.

Why would she want this? And who would she be trying to seduce?

The realisation hit you in an instant. Shit, it can't be you, right? I mean, she does call you cute and hugs you a lot and gets the occasional annoying erection when you do things together - oh crap...

Even if you weren't the target, just being around Crystal would make you lust after her. And, knowing your sister, you would submit.

The thought of this fills you with a strange desire. Would it really be all that bad? You knew how hot your confident older sister was. You'd had thoughts about her from time to time, and that was without any **** influencing you at all.

It was a crazy idea, and you weren't even sure if the thing was real, but you had seen enough movies and comics to know how most women liked to lead, having the men as submissive partners. Yes, please.

Part of you couldn't believe you were doing this as you put the booklet back in the box with the white bottles. You took it to Crystal's room and knocked on the door.

"Hi, um, a package came for you."

"What? A package... Oh shit, quick get inside."

She practically yanked you into her bedroom. She tore the box from your arms and ripped it open. She squealed in excitement. Then she paused and looked at you.

"Why isn't the box taped shut?"

"I thought it was for me," you lied. "I saw what was in it. I wanted to give it back to you."

"You want me to drink this?"

"Yeah. I mean it's probably fake but imagine how cool it would be if it were real."

"If I didn't know better I'd say you wanted me to be your Alpha, little brother." She smirked.

"I mean, it is kind of a hot idea," you laughed.

Crystal didn't laugh, but her smile grew wider.

"Let's get started then. I'll drink the first bottle and you tell me if you feel anything."

"Um, okay, sure sis."

She wrenched open the bottle and chugged it down.

"What do you think, little bro? Feel anything?"

You look her up and down. Same Crystal as before.

"I don't think so..."

She frowns and chucks the empty bottle onto her floor.

"Stupid mail-order scams."