This was after Robert sired his first child (the illegitimate) Mya Stone. Though not disloyal to his friends and fierce in battle, Lyanna Stark noted that even if he did love her, he would never keep to one bed. Robert had a rather difficult time with responsibility, and by extension, alcohol. He maintained a ferocious voice throughout his life, one that could rally whole armies to him. Robert wore an antlered helm in combat that gave him an almost godlike appearance, and was unstoppable in a fight he proved stunningly strong even after he had fallen into gluttony and drunkenness, to the point that even after his death Jaime Lannister considered the man stronger than him. However, Robert was also a fierce swordsman, described as entering the Battle of the Bells with a sword in hand and surviving. Robert was incredibly strong all of his life, and wielded a warhammer in battle that proved nigh-impossible for anyone else to wield. However, his relationship with the northerner meant that he lost love for both his brothers. Robert Baratheon trusted Ned Stark with his life, having grown up alongside him since they were children and become brothers in all but name. He resented Stannis ever since he became king for allowing Prince Viserys and Princess Daenerys to escape his grasp at the end of the Rebellion, and thus never showed him the love or respect that Stannis truly deserved - Storm's End was rightfully his but Robert gave it to Renly after Jon Arryn died, Robert would have found an able, efficient and tireless Hand in his brother, but instead turned his eyes North to his friend Ned Stark.
Robert had a deep capacity for resentfulness, as he proved in several regards: namely his eldest brother Stannis. However, this meant that if he were to return to war, he would be unrelenting and ferocious, as proven during the Greyjoy Rebellion. He was disdainful at some of the processes that were required to govern the realm, leaving it to his small council. He did not commit completely to the day-to-day governance of his realm - he preferred to indulge himself en masse and this cost him a great deal of respect that he had gained so gloriously during his heroic Rebellion against the Mad King. In the end, he found that winning a kingdom was far more fun than actually ruling one.
He sometimes joked that he would like to leave everything behind to become a hedge knight, lusting for freedom from the responsibility that a crown and throne thrust upon him. Very few people saw him as more than a drunken sot of a man. Aside from Jon Arryn he had few true friends at court, and didn't trust anyone other than Ned Stark or the aforementioned man, not even his brothers, with whom he mutually disliked. Some of his legendary humour left him, and his temper came out more and more often, especially if the Targaryen name was mentioned - even though he had personally killed Rhaegar in a legendary duel that was the stuff of songs in the present, and the Mad King was dead, Robert's fiery hatred of the Targaryens clung to him like a disease. With the battles and wars won, and with his family and Kingsguard disapproving of him taking part in tourneys and melees, Robert lost his former vigour and became fat and somewhat indolent. Some of the joy went out of Robert upon the death of Lyanna, and this only increased as his loveless marriage with Cersei continued - they hated each other, and barely made a secret of that hatred. Robert was probably grateful that someone else bloodied their hands with the Targaryen children and not him. It was suggested that Robert was ashamed of some of the sacrifices that it took to win him the throne, namely the savage deaths of Prince Aegon and Princess Rhaenys Targaryen, but at the time Robert hatefully called them "dragonspawn" and did not punish either Tywin Lannister or Gregor Clegane for their murder. He had no love of politicking or intrigue. He celebrated hard as well, but as a younger man always took care to maintain his peak fitness. He was never happier than fighting at the lists or on the battlefield. Immensely charismatic, he won people to his side and to his cause through sheer personal magnetism - men who fought to kill him one day would be sharing a drink with him the next. He was often red-faced from drinking, and had dark circles under his eyes he often walked awkwardly, as if he were still in his cups. After becoming king, however, he became fat, indulgent and his beard became thick and dense, hiding two chins. He was frequently described as muscular, black-haired, clean-shaven and extremely handsome, and in battle he wore an antlered helm. As a younger man, Robert was proud, tall, commanding and fierce in battle, and all agree after he died that Robert was a superb soldier.