Serena was in a pickle with her mentality and her instincts. One side said eat while the other kept her humanity and kept saying or rather screaming "please no". In the end she had no choice, she accepted it and dug in.
Serena POV: I hate my new life, i'm eating poop and it tastes good, I am a pathetic fly and I am weak. Could this get any worse.
System: It can get worse because the creature you absorbed has no magic in it meaning it is a normal creature. Basically you are incapable of magic and not even Rank 1, a Rookie.
Serena still being a rational woman just decided to stop thinking and let herself be taken over by instinct.
System: You have acquired 23% DNA of magic creature Rank 3, Leaf Raptor. Eat all of the excrement and you will have an estimated 46% DNA of Leaf Raptor.
Serena: Aww sweet so can I turn into that instead now?
System: No you need 100% DNA and need Magic Energy to grow it up to adult, lucky for you this is a Rank 3 monster which is unusual for this species, they are usually Capped and Rank 2.
Serena was happy with what she heard, but soon remembered she needed to eat more, she also noticed that she gained Magic Energy from eating it so she just got it over with, she also noticed she has an increased sense of smell, so she used it to track where the Leaf Raptor went so she can possibly get more DNA from it.
Serena: Wait if I absorbed the Armored Fly can I absorb other creatures?
System: Yes but you have used one and you have three so now you have two remaining, but you cannot use it on monsters above Rank 5 since you are currently at Rank 3 and will need to get to Rank 4 beforehand.
Serena: So I need to get to rank 4 before I get to rank 5?
System: Yes.
Serena: Ok then let's end this as soon as possible because I hate eating something that tastes like this, it tastes good but its only because of the flys tastebuds. . . If they can even be called that with this long tube of a mouth.
So afterwards Serena followed the smell of the Leaf Raptor, finding it was hard because she had accidentally gotten stuck in a spiderweb. Luckily the spider that lived there was dead so it took her a hour to get off. She took a day but finally found the Leaf Raptor and saw something she was hoping she would not have to see soon.
More piles of poop, her mentality wasn't strong enough to resist and saw a huge amount of piles, she just let loose and went ahead and ate it all. The Leaf Raptor was with a pack of more Leaf Raptors so they were just resting after hours of walking and looking around their territory for food.
They had heard an annoying buzzing sound moving closer to them and saw a bug, they were carnivorous and since this world is Eat or Be Eaten, they had to eat whatever they could get.
Serena felt a strange feeling, knowing it wasn't good she turned around to see the pack of Leaf Raptors preparing to leap at her, luckily she was a 78% DNA so she just needed a bit more.
Serena POV: Well, I was hoping this would be easier but just as I dealt with the fly this is a good time for a meme before I possibly die.
Oh Sh*t, Here We Go Again.