Unconscious Grasping to a Self

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.

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

From AN8.35, we have the case of an elaborate grandiose grasping by an ethical persion:

The heart’s wish of an ethical person succeeds because of their purity.

Next, someone gives to ascetics or brahmins such things as food, drink, clothing, vehicles; garlands, fragrance, and makeup; and bed, house, and lighting. Whatever they give, they expect something back. And they’ve heard: ‘The Gods of Brahmā’s Host are long-lived, beautiful, and very happy.’ It occurs to them: ‘If only, when my body breaks up, after death, I would be reborn in the company of the Gods of Brahmā’s Host!’ They settle on that idea, concentrate on it and develop it.

As they’ve settled for less and not developed further, their idea leads to rebirth there. When their body breaks up, after death, they’re reborn in the company of the Gods of Brahmā’s Host. But I say that this is only for those of ethical conduct, not for the unethical.

Wishes, be they simple or grandiose, entangle us in grasping at the continued existence of identity view, that illusion of a self. Yet even the grandiose story ends. All those grandiose features and details die.

When they know a thought with their mind, they don’t get caught up in the features and details. If the faculty of mind were left unrestrained, bad unskillful qualities of desire and aversion would become overwhelming. For this reason, they practice restraint, protecting the faculty of mind, and achieving its restraint. When they have this noble sense restraint, they experience an unsullied bliss inside themselves.

-- MN 51

To live without wishes in this very life, extinguished, requires understanding and letting go of wishes. Perhaps your writing is simply a way for you to understand what it is you or others might be holding on to. In that understanding of the inevitable impermanence of the grasped might also be the letting go.

They live without wishes in the present life, extinguished, cooled, experiencing bliss, having become holy in themselves.

OP: In daily life, I guess my self-grasping is not very salient; people tell me I'm considerate, open.

Just because you're considerate and open, doesn't mean you're not self-grasping.

Even if you think "I am considerate and open" and feel happy about that, that's already self-grasping because you're associating some mental ideas to your self.

This can be see in SN 22.59:

"And is that which is inconstant easeful or stressful?"

"Stressful, lord."

"And is it fitting to regard what is inconstant, stressful, subject to change as: 'This is mine. This is my self. This is what I am'?"

"No, lord."

However, for lay persons who are not stream enterers, I think recollecting examples of when you were considerate and open, is more skillful than having the three poisons occupying the mind, because it brings some joy to your mind and removes the three poisons.

We see recollection of virtues and generosity in AN 11.13:

"Furthermore, there is the case where you recollect your own virtues: '[They are] untorn, unbroken, unspotted, unsplattered, liberating, praised by the wise, untarnished, conducive to concentration.' At any time when a disciple of the noble ones is recollecting virtue, his mind is not overcome with passion, not overcome with aversion, not overcome with delusion. His mind heads straight, based on virtue. And when the mind is headed straight, the disciple of the noble ones gains a sense of the goal, gains a sense of the Dhamma, gains joy connected with the Dhamma. In one who is joyful, rapture arises. In one who is rapturous, the body grows calm. One whose body is calmed experiences ease. In one at ease, the mind becomes concentrated.

"Mahanama, you should develop this recollection of virtue while you are walking, while you are standing, while you are sitting, while you are lying down, while you are busy at work, while you are resting in your home crowded with children.

"Furthermore, there is the case where you recollect your own generosity: 'It is a gain, a great gain for me, that — among people overcome with the stain of possessiveness — I live at home, my awareness cleansed of the stain of possessiveness, freely generous, openhanded, delighting in being magnanimous, responsive to requests, delighting in the distribution of alms.' At any time when a disciple of the noble ones is recollecting generosity, his mind is not overcome with passion, not overcome with aversion, not overcome with delusion. His mind heads straight, based on generosity. And when the mind is headed straight, the disciple of the noble ones gains a sense of the goal, gains a sense of the Dhamma, gains joy connected with the Dhamma. In one who is joyful, rapture arises. In one who is rapturous, the body grows calm. One whose body is calmed experiences ease. In one at ease, the mind becomes concentrated.

So, it's OK to recollect examples of one's virtues and generosity.

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

Oh yes, from SN 42.2:

Then Talaputa, the head of an acting troupe, went to the Blessed One and, on arrival, having bowed down to him, sat to one side. As he was sitting there he said to the Blessed One: "Lord, I have heard that it has been passed down by the ancient teaching lineage of actors that 'When an actor on the stage, in the midst of a festival, makes people laugh & gives them delight with his imitation of reality, then with the breakup of the body, after death, he is reborn in the company of the laughing devas.' What does the Blessed One have to say about that?"

"Apparently, headman, I haven't been able to get past you by saying, 'Enough, headman, put that aside. Don't ask me that.' So I will simply answer you. Any beings who are not devoid of passion to begin with, who are bound by the bond of passion, focus with even more passion on things inspiring passion presented by an actor on stage in the midst of a festival. Any beings who are not devoid of aversion to begin with, who are bound by the bond of aversion, focus with even more aversion on things inspiring aversion presented by an actor on stage in the midst of a festival. Any beings who are not devoid of delusion to begin with, who are bound by the bond of delusion, focus with even more delusion on things inspiring delusion presented by an actor on stage in the midst of a festival. Thus the actor — himself intoxicated & heedless, having made others intoxicated & heedless — with the breakup of the body, after death, is reborn in what is called the hell of laughter. But if he holds such a view as this: 'When an actor on the stage, in the midst of a festival, makes people laugh & gives them delight with his imitation of reality, then with the breakup of the body, after death, he is reborn in the company of the laughing devas,' that is his wrong view. Now, there are two destinations for a person with wrong view, I tell you: either hell or the animal womb."

Well, it's not the same as your case, but it's similar.