Having been a consumer of... shall we say, niche content, all your life, you sit down and write "No one but me will ever be aware of any changes I make using the pen. And no one will ever use the pen without my express permission, and even then, they will only use it for the reason I intend them to."
The ink glowed gold for a moment, before turning green and then black. That should ensure that there aren't any messy consequences from someone else using it. You thought for a minute, before putting your pen to paper, and writing, "Nothing I write using this pen will change my personality in any way, unless I specify it. If I do not, my actions will be filtered through the resulting personality. If it does, then the moment I pick up the pen, my personality will revert. No matter what personality I have, I have a habit of picking up the pen and twirling it in my hands."
The ink glowed once more. "I will remember reality as it is now, and as it is after I change it. These two sets of memories will be perfect, and easily distinguishable from one another."
After this line finished glowing, you thought of a sure-fire way to test the validity of this pen. "All women that work at this company are ditzy, kind, and submissive catgirls, with large cat ears and fluffy tails. A catgirl's eye, hair, and fur colours are all the same, and said colour is unique between each catgirl. All catgirls have thin, lithe bodies, with small breasts, hips, and asses. They all have a verbal tic, where they will insert a "y" between the letter N and any vowel. The natural length of a catgirl's hair varies between ass length and floor length, although they all adore fashion and hair styling, and makeup of all sorts. They will normally wear midriff revealing crop-tops with the company's logo emblazoned on the right breast, and minishorts with the company's logo on the right ass cheek. When it is cold, however, they wear hoodies and yoga pants. Despite their ditzy nature, they are all stellar employees. When on break, they find the nearest non-catgirl lap, and curl up in it, or they nap cutely in the breakroom's human sized kitty trees. They have other feline instincts as well."
The writing glows, and it's not long before an orange haired catgirl dashes into your office. "Hi boss!" Your new memories tell you that this was Jodie, your new secretary- or secre-kitty, in this case. "I've got all your meetings for today! You have a 2:30 meeting, and one at four- although that one's nyot gonnya be a long one though." You absentmindedly fiddle with your pen and ask her who the meetings are with. "Well, the first meeting, at two thirty, is with your nyew bosses- talking about responsabilities and thing if you were to ask me-" Jodie answers, her tail waving around, "But the four is with HR- mostly paperwork I think."
"Ok," You answer, "Keep... doing what it is you like doing," you say, "But, do remind me when it's... say two o'clock, alright?"
"Yes sir!" Jodie said, rushing out of your office as fast as she came in. You chuckle to yourself, and put your pen to use once more. "Jodie is now named Tangerine, and is always upbeat and peppy."
The ink glows once more, and you wonder what to do...