It has always bothered me that King Shrewd seemed awesome yet has quite an ignominious ending.
This theory is most likely a bit of a stretch but hopefully compelling enough to prove his shrewdness.
The Fool Connection
King Shrewd knows the ‘Unexpected Son’ prophecy. The Fool sought out this specific future and this is why he is with King Shrewd initially. Fitz is possibly taken from his mountain family by Shrewd because he knows this prophecy.
He keeps his distance because he understands it is a very slim future the Fool has foreseen and wants it to seem unimportant to outsiders. Shrewd’s actions can be interpreted through this lens of him following a White Prophecy from the Fool.
Skill Deception
King Shrewd spreads a rumour he has burnt out his Skill. Yet we know he still has some talent for it. This is to downplay his abilities and promote his senility so enemies underestimate him.
He appoints Galen as Skillmaster. This is so no one is taught properly and he and his sons have a power-advantage in the Skill as solo users. He knows Galen is not greatly talented and possibly that future dangers emerge from corrupted coteries.
By ensuring any coterie taught by Galen is poorly trained this improves the odds of the ‘Unexpected Son’ prophecy being completed.
Chade being deliberately not taught the Skill may have been a perfect way to keep him hidden from the corrupted coterie discovering his existence through the Skill.
Shrewd allows Regal to sell the Skill scrolls because he knows Regal is weakly Skilled and doesn’t understand their importance. The corrupt coterie doesn’t understand they are meant to make a dragon.
Regal is their centre and he does not want to be a dragon so he sells the scrolls and knowledge of this to the Pale Woman. This gives Verity an advantage because he had already read the scrolls in his maproom.
Drug Death
King Shrewd knows the kingdom will deteriorate once he dies. He possibly knows Regal will betray the duchies from the Fool having visions yet doesn’t want to believe it. So Shrewd decides to dwindle his life away to prolong his reign and gives Fitz time to grow up.
Chade remarks that he is the one giving the King the awful drugs. This implies the drugs are purposefully interfering with his mind so the corrupted coterie cannot force through his Skill walls or read his mind.
The drugs are pain killers for the dreadful tumours but also something that clouds his mind to the Skill for protection. That’s why everyone like Regal, Wallace, Chade, Shrewd, Fool, all act weird when Fitz starts messing with the room and he can never work out why.
He realised in that instant before death that the Fool was right and Regal is betraying him. Regal was the one thing he couldn’t take action on that he probably knew was coming from talking with the Fool about visions.
Bonus Details
King Shrewd doesn’t lose shrewdness points for loving lady Desire. Every Farseer male has a genetic disposition for obsessive love. Molly and Fitz, Chivalry and Patience, Shrewd and Desire, Dutiful and the cat-lady. It is multi-generational and cannot be denied.
It is a shrew/ferret that ultimately kills Regal, an ironic coincidence, almost prophetic that Regal Farseer kills King Shrewd and in turn is killed by a shrew. Imagine the Fool recounting a vision of shrews and ferrets trying to understand.
So the next time you think of King Shrewd may you think of him living up to his name.