Unconscious Grasping to a Self In daily life, I guess my self-grasping is not very salient; people tell me I'm considerate, open. However, I've written stories in the past, and in my fiction I project these fantasies that are incredibly grandiose and self-absorbed. I'm not sure what to conclude here.

Is it possible to have an unaware, unconscious self-grasping (which would here transpire in my stories)?

Or perhaps, could writing down and elaborating grandiose, self-themed stories exacerbate self-grasping which would otherwise be much less?

I am somewhat confused about this as, as I said, these stories seem not to fit my day to day personality, but clearly possess important themes of self-grasping.
OP: Is it possible to have an unaware, unconscious self-grasping (which would here transpire in my stories)?

There are 18 internal and external views across past, present and future making a total of 108 views of self rooted in carving.
18 Internal Preoccupations with Craving

(1) “I am”
(2) “I am this [I am like this]”
(3) “Thus am I [I am like that]”
(4) “I am otherwise”
(5) “I do not exist”
(6) “I exist”
(7) “May I be”
(8) “May I be this [be like this]”
(9) “May I be so [be like that]”
(10) “May I otherwise”
(11) “I might be”
(12) “I might be this [be like this]”
(13) “I might be that [be like that]”
(14) “I might be otherwise”
(15) “I shall be”
(16) “I shall be this [be like this]”
(17) “I shall be so [be like that]”
(18) “I shall be otherwise”

Tanhā Jālinī Sutta / (Vicarita) Tanha Sutta
For an untrained person, any externals experience always result in the self-view. What one should do is to contemplate perceptions, thought, view as not-self. To to this one have to develop awareness into this process.


the eye, form, eye-consciousness, eye-contact, feeling, craving, are not-self,
the ear, sounds, ear-consciousness, ear-contact, feeling, craving, are not-self,
the nose, smells, nose-consciousness, nose-contact, feeling, craving, are not-self,
the tongue, sounds, tongue-consciousness, tongue-contact, feeling, craving, are not-self,
the body, touches, body-consciousness, body-contact, feeling, craving, are not-self,
the mind, mind-objects, mind-consciousness, mind-contact, feeling, craving, are not-self.


Cha Chakka Sutta

OP: could writing down and elaborating grandiose, self-themed stories exacerbate self-grasping which would otherwise be much less?

Self-grasping is always there. (Only at streem-entry is this broke.) More you think about oneself (108 through paths above) it is reinforced.
If

perceptions,
thoughts, or
views

do arise one should straighten them by contemplating:

Impermanent as impermanent
Painful as painful
Not-self as not-self
Impure [unattractive or repulsive] as impure

See Vipallasa Sutta
When creating these stories your self-view may be reinforced. If you do this as living maybe you can take a step back and try to write stories without too much self-centeredness. When you have to write something and the above Vipallasa arises contemplate on the antidote.
This and this answer also might be of interest on how to eliminate self-view arising.