As you opened the door it was a little hard to see what was inside since it was fairly dark, but you could at least tell that someone was inside there.
you spoke out "Um... Excuse me for intruding... I think i'm your partner..." You saw some movement and continued "My name's Sara, I hope we can get along." Your eye's adjusting and saw that the movement was coming from under the sheets of a bed.
Your partner now looking at you said "Ah hello... Interesting... I got paired with a fellow succubus, my names Maria." Something felt odd in the air as Maria climbed out of the sheets. You saw the silhouette of a well figured woman, you supposed the age of a succubus and their bodies wouldn't correlate that much.
A little uneasy you said "A Succubus? No, I'm human." Maria walked her way towards you and looked you over with her eyes that were as dark as the room.
After a good look and a sniff she said "A human with so much of that type of magic in them... unlikely... no, impossible... I can tell that you are a succubus just by that store of power you have in you... Quite a good amount for one whose eyes are still white. Have you not joined the orphaned sinners yet?"
"No, no I was born and raised by two humans with my human twin brother. I am no doubt a human!"
"i'll take that as a no then... Only those who see themselves and are actually succubus join orphaned sinners... I suppose they wouldn't mind if I did this too then."
"what do you-" Maria got close to you and then picked you and moved quickly to put you on the unused bed in the room. Underneath Maria you protested "W-w-wait! What are you doing?!?"
"Don't worry, i'm not an Incubus so this wont hurt at all." Your lips met and while you tried to protest the kiss she inevitably got her tongue through your lips and into your mouth, but almost as soon as it entered it exited. Maria got off of you leaving you very confused. "Your not going to do more?" you said concerned.
Maria chuckled and said "What you wanted more? I did the minimum I needed to do, after the first year sexual acts even as yuri get a tad boring. Call me lazy but there just isn't much reason to invoke the sexuality of another succubus... or even an incubus. regardless it seems your magic is starting to actually work now, oh your nipples are so cute..." You looked to your chest and saw that your nipples were starting to lengthen and poke through your shirt and your hips were also starting to grow.
Very concerned you nearly yelled "What did you do to me?!?" you felt your chest start to lift and your shirt start to strain.
"I simply loosened the magic locks on your body allowing your natural magic to start circulating through your body, that magic now is making your Succubus body mature. Trust me without the proper body or magic you probably will fail this test. here let me help you with that tight shirt of yours..." she got closer to you and started to unbutton your blouse revealing your little A-cup breasts which were still maturing. You could easily tell that your body was still growing and stretching, your hair continuing to lengthen, your "puberty" progressing quickly. The magic in your body flowing faster and faster your breasts continually getting plumper and plumper till they rested at E-cups, your hips having flared out, and your nether regions had matured. With a lot of your magic having dispersed through your body to make you grow you felt tired and closed your eyes for a few moments. In those moments it felt as if the heat left your body, you retreated your tongue in your mouth as some of your teeth grew more spiky, and your eyes burned for a moment. You opened your eyes and Maria said "Oh you have matured into a fine body for a Succubus... I suppose your hungry now though, I know the best place for us to eat. I'll get your some of my clothes for now though, those kids clothes on you won't do anything for that adult body."
you got up and shedding your clothes looked into a mirror and saw your body like you would see a stranger's. You were definitely in the body of an adult, looking at your face you couldn't really argue that you were human. Your face was so pale and testing your teeth with your finger they were awfully sharp. You didn't notice but the lights were still off so wanting some illumination you flicked the light switch and was instantly blinded.
You let out a small screech and Maria opened the door and asked "What di, EEE! Turn off that light!" the room went dark and Maria asked "What the heck were you doing?"
"I just wanted to see a little better so I turned on a light"
"Our black eyes work best in this darkness, while elder Succubus may be able to see ok in sunlight we cannot. We need darkness like this, either way I got your clothes ready. Don't turn on any of the lights." You followed her advice as she gave you some of her clothes and a pair of sunglasses. You put on the clothes somewhat surprised that they looked like the clothes a normal person would have. A blouse, A coat, some jeans, and undergarments. The clothes mostly fit well except for the undergarments which the top was a little tight. You put the sunglasses on and saw that you couldn't see out of them even with your good nocturnal vision. Maria chuckled a bit and said "Those are for outside, they simulate this type of environmental lighting so we can actually see without going blind. Quick catch!" Maria tossed you something that you caught. Looking at it the thing appeared to be some sort of nut. Maria explained "We call them sin seeds, suck on it while we go to that little restaurant I know. You'd probably collapse from exhaustion otherwise, you used a lot of magic during your change."
You said "thanks..." in your more mature voice and put the sin seed into your mouth and started to suck on it. You started to feel less tired and more energized.
Maria put on her sunglasses and said "All right then, girl's night out on town!" Where did she bring you to though?