Yes, Diego is pretty much expendable. Of course, in Crusader Kings everybody is expendable.
A fighter and a rogue meet in an inn
Kuipy (King of Leon)
They say that in Normandy every story begins with a meal, but nowhere better than in the good city of Eu, and, there, nowhere better than at the Auberge du bon soldat. The place names meant the Good Soldier’s Inn, but what soldiers came in were only plump militiamen, with jovial faces and nice uniforms and rusted swords.
The kings cherished the city as the last remnant of their old homeland, and gave its bourgeois many charts and privileges, so that many Normans, unhappy under the Saxon or Burgundian rule, flocked to it and made it more prosperous than any other port of the Channel.
For the first time in centuries the kingdom of Normandy had been in peace for more than a decade, for the first time it stood secured, having extended itself from Orkney to Seville. Now it reaped the benefice of stability and an improved administration. Everywhere forests were felled to be replaced by fields and pastures, everywhere banalities were built and roads paved. Everywhere plenty replace thrift, and prosperity ruin; but nowhere as much as in Eu, or so they said.
In 1221 the auberge belonged to Mathilde, a tall, strong, dark-eyed woman whose strong voice and sharp wits terrorized staff and customers alike. King Lovell had given it to her, some seventeen years ago, when her hair was still black, her hips slender, and her upper lip hairless, and with canny and obstinate efforts she had made it one the best hostels in that bustling town. Although courteous, she had never been affectionate in the slightest way with her clients. But that morning, when a blonde, smiling young man, with dark blue eyes and a clean-shaved face pushed the door with a bundle over his shoulder, she threw herself in his arms.
“Rogerin! How you’ve changed!”
“I can see many things have changed at the inn, too.”
“Have you eaten well?”
At that he had to smile. “I did not starve at the court. My father is most generous with us” he added, almost resentfully.
“How long will you stay?”
“I don't know yet. It all depends on...”
Suddenly he froze and looked around him. Sitting at a table with a jug of cider, another guest was sitting, apparently oblivious to their conversation, but with an ominous, suspicious look about him.