Behold is a verb that means to look at something, to observe or see it. The past tense is beheld. Someone can be a beholder. It is often used in command form, telling someone else to Behold!
Beholden is an adjective that means to owe someone something, to be obligated or in debt.
There is no clear evidence as to why beholden has such a different definition than the word from which it originated. Only that beholden did in fact come from the past participle of behold.
Another idiom attached to this word lo and behold, which originated as an interjection of awe or surprise. Now it is most often used in jest in describing something that shouldn’t be surprising at all.
First Christian Church will host “Behold The Lamb of God” at 6 p.m. on Saturday, Dec. 20 and Sunday, Dec. 21. [The Brazil Times]
It is the most compelling and beautiful physical evidence of Franco-American amity I have ever beheld, with the possible exception of another, much larger statue in New York Harbor. [New York Times]
The final complication is that of course Microsoft is a US company beholden to US law but the information is in Ireland and thus presumably (along with that portion of Microsoft that is in Ireland) beholden to Irish law. [Forbes]
Once on board the Boeing 737, the Ebenezer Scrooge-ish passenger received again another jolly, festive greeting from a flight attendant. Lo and behold, he burst into anger and yelled “Don’t say, “Merry Christmas!'” Everyone was stunned. [International Business Times]