The offence is reported in a single verse and then dropped. Israel dwelt in that land, and Reuben went and lay with Bilhah his father's concubine, and Israel heard it. The narrative moves straight on to a list of Jacob's sons without comment. Whether the act is understood as lust or as a claim on his father's position, which is how a similar act is read later in the books of Samuel, the text does not say.
The sentence comes at the deathbed, chapters later. Reuben is addressed first, as the firstborn, the beginning of his father's strength, excellent in dignity and power, and then unstable as water, and told he shall not excel. Chronicles states the consequence as a matter of record: the birthright was given to the sons of Joseph, while the rule went to Judah, and the genealogy is not reckoned by the birthright.
The rest of what the text gives him runs against the verdict. He brings his mother mandrakes from the field as a boy. When the brothers plan to kill Joseph he talks them into a pit instead, intending to come back for him, and tears his clothes when he finds the pit empty. Years later he offers his own two sons to be put to death if he fails to bring Benjamin home, an offer so badly judged that Jacob ignores it, and Judah has to make the case again properly.
That is the shape of him throughout. He tries, at the right moments, in the wrong way, and the family passes him over.