Natsu implants a few triggers on Grey

After being explained the job, Natsu got on his way home to get Happy, which he had left there again because he was intending on using the note. However, if they were going out of town, sending him home every time he wanted to do something would simply not work, so he had to do something else.

"Happy will not be aware of any sexual actions from Natsu Dragneel, unless he wants him to be aware, in which case he will see them as something normal. Happy will be Natsu's wingman and help him in his sexcapades whenever he asks." He wrote that last part as a catch-all clause just in case. Maybe he could have him stand watch to avoid getting caught or something like that.

After picking up Happy and grabbing something to bite on the way, Natsu got to the agreed upon place, where Grey was already waiting, and together they departed towards their destination. According to Grey, it would only take a couple days to get there on foot if they traversed the forest, rather than going around it. There was a train that would also take them there, but Natsu refused, for obvious reasons. Although he did wonder if the note could cure his motion sickness if he used that new opportunity for sex, he wasn't very trilled to try that out. Plus, the trip on foot was longer and, since none of them was afraid to travel through the forest, they would have less company, which would give him more opportunities to attempt something with Grey.

And an opportunity did arise around midday, when they found a nice clearing and decided to get some rest, make a fire (which Natsu could easily handle) and cook something to eat. While Grey created a table and seats out of ice, Natsu went outside of the clearing to look for wood, which would allow him to use the note without being seen.

"Grey Fullbuster is bisexual, and will gradually become attracted to Natsu Dragneel." He wrote, thinking that would be a good start. He pondered a bit before continuing.
"Grey Fullbuster has several trigger phrases that, when said by Natsu Dragneel and directed at him, will make him behave in certain ways. When a trigger is used on him, he will not realize anything is out of the ordinary. The triggers are as follows:

Soft Lips: Grey will give Natsu a deep kiss. If the trigger is followed by a name, Grey will kiss that person instead.
Full Mast: Grey will become increasedly aroused by the moment, but he will be unable to masturbate or otherwise take care of it himself.
Birthday Suit: Grey will strip of all clothes and remain unaware he's naked.
Hands-On: Grey will start masturbating (even if under the effects of Horny Grey), but can't cum by himself no matter how much he tries. If the trigger is followed by a name, he will masturbate that person instead.
White Release: When used while under the effects of a trigger that prevents him from cumming, Grey will now be allowed to cum.
Grey Nutbuster: Grey will instantly cum, even if under the effects of a trigger that prevents him from cumming.
Lip Service: Grey will be overcome with an overwhelming need to perform oral sex on someone and let them cum wherever they choose. If the trigger is followed by a name, Grey will perform oral sex on that person instead.
Bottoms up: Grey will be overcome with an overwhelming need of getting his ass fucked. If the trigger is followed by a name, he will need anal sex from that person specifically. If the name is his own, he will start to anally masturbate, but can't touch his dick unless Hands-On is also used.
Fuckboy: Grey will be overcome with an overwhelming need of fucking someone. If the trigger is followed by a name, he will fuck that person. If the trigger is followed by a body part, he will fuck that specific body part (if penetration is not possible, he will grind his dick against that part).
Little Pet: Grey will become submissive and gladly obey any command given to him. If the trigger refers to him as someone's little pet, he will obey only that person's commands.
Back to normal: The effect of all triggers will immediately end. Grey will not remember any actions taken under the effect of the triggers, unless he is told to remember some or all parts, in which case he will see them as normal and voluntary actions. Whether he remembers or not, he will either ignore or rationalize any consequences from those actions."

Natsu looked at it once more, and he noticed something. He tried to cover all possibilities by allowing the triggers to make him do stuff to other people, and he was planning to have some fun with that in the future, but there was a possible issue with that, which he promptly corrected: "None of the triggers will make Grey do anything to an unwilling party. He will not perform any sexual actions without consent."

Finally happy with what he had written, he quickly picked up some dry wood and returned to the clearing. "Hey, Grey!" he said when he was nearing the camp, both to let him know he was about to arrive, and to get his attention to use a trigger. He was planning on using Birthday Suit first and improvise from there, but as he got in the clearing he quickly realized how utterly useless that trigger was (and how he should have realized while writing it) as a fully naked Grey greeted him "Hey, Natsu, I'm already done, you got the wood?"

Oh, Natsu had the wood alright, how couldn't he with Grey displaying his dick so naturally? He was going to start with the tamer triggers and build up from there, but seeing this, perhaps this one time he will just skip straight into the heavier stuff...