Unlike the first two Blackadders and Baldricks, the two Lord Percys are almost identical; both are portrayed as dim-witted, gullible and foppish. In the first series, Percy is Duke of Northumberland, while in the second he is heir to the title. The title of Duke of Northumberland was not in fact held by a real person surnamed Percy until 1766 when Hugh Percy, born Hugh Smithson, was awarded the title, although the title of the Earl of Northumberland was granted to a Percy in 1377.
The character did not appear again after series two after Tim McInnerny declined to play the part for fear of being typecast for playing idiots, and only returned to the series full-time when he played the more serious Captain Darling in the fourth series of the franchise, Blackadder Goes Forth. The character of the inept upper class Englishman is replaced in series three and four by Prince George, The Prince Regent, and Lieutenant George respectively, both characters being played by Hugh Laurie. (McInnerny did appear in the third season episode "Nob and Nobility", in which he plays Topper, an upper-class fop who turns out to be the Scarlet Pimpernel. Likewise Laurie appeared in two episodes in the second season, as Simon Partridge in "Beer", and as Prince Ludwig the Indestructible in "Chains".)
Percy is introduced in the first series as Percy, Duke of Northumberland. In the first series Percy accompanies both Prince Edmund and Baldrick on all their journeys. At one point Percy becomes the bishop of Ramsgate when Edmund becomes the Archbishop of Canterbury; he also believes he has a finger bone belonging to Jesus Christ. However Baldrick informs him that it is a fake by displaying his own collection of 10 other "Jesus fingers". In the episode "The Black Seal", Percy accidentally puts poison in the castle's entire wine supply while trying to rescue Prince Edmund from a group of maniacs. While rescuing Edmund, Percy inevitably kills him and the whole royal court when they drink the tainted wine. Percy and Baldrick run in and futilely shout, "Don't drink the wine!" immediately after.
In this series, Lord Percy Percy (died 1566) is once again portrayed as a stupid "upper class twit". Percy has a much larger role in series two, however; this is illustrated by his almost total involvement in all of Blackadder's pursuits (whether or not Blackadder actually welcomes his input). Percy is (among other things) temporarily the best man at Blackadder's wedding, assistant Lord High Executioner and a shipmate on Blackadder's ill-fated voyage to France (despite a pronounced aquaphobia stemming from a childhood incident where he was "savaged by a turbot"). At one point, while trying to master alchemy, Percy creates a green substance that Edmund sarcastically calls "Green" and attempts to turn it into something valuable. He is shown to have a terrible female record; whilst the occasional girlfriend is mentioned, he is more often seen using rather unconvincing chat up lines on various females, and, at one point, Baldrick, who was wearing a wig and a dress while acting as a bridesmaid. Percy promptly falls in love with him, not recognizing Baldrick.
Percy is murdered along with the rest of the permanent cast of Blackadder II by Prince Ludwig in the last episode, "Chains".