In Beowulf, how was Heorot the center of both life and death?

In Beowulf, the mead-hall Heorot is the center of the Dane's tribal culture.  It gives life to King Hrothgar and Beowulf in terms of establishing the Anglo-Saxon name and reputation, but it is also a place of death where the monster Grendel revenges himself against the Anglo-Saxons out of jealousy and envy (regarding their Comitatus, or King-Thane bond).

Heorot is the embodiment of this sacred bond between King and thanes.  According to my notes:

“Warriors were loyal to the king and would fight to the death for him, surrender was cowardly. Honor and loyalty to the tribe and to the king were more important, in a way, than material goods, for being remembered well after death, where you could not take material objects, was very important.”

In the poem itself, Heorot is first described thusly (Heany translation):

The fortunes of war favoured Hrothgar. 
Friends and kinsmen flocked to his ranks, 
young followers, a force that grew 
to be a mighty army. So his mind turned 
to hall-building: he handed down orders 
for men to work on a great mead-hall 
meant to be a wonder of the world forever; 
it would be his throne-room and there he would dispense 
his God-given goods to young and old - 
but not the common land or people's lives. 
Far and wide through the world, I have heard, 
orders for work to adorn that wallstead 
were sent to many peoples. And soon it stood there, 
finished and ready, in full view, 
the hall of halls. Heorot was the name 
he had settled on it, whose utterance was law. 
Nor did he renege, but doled out rings 
and torques at the table. The hall towered, 
its gables wide and high and awaiting 
a barbarous burning. That doom abided, 
but in time it would come: the killer instinct 
unleashed among in-laws, the blood-lust rampant.

As immediately as it is described as a place of community, charity, and wonder ("God-given goods"), it is tagged with foreboding doom ("in time it would come: the killer instinct..the blood-lust rampant").

In this way, Heorot is not unlike heaven, a place where God (Hrothgar) anoints his chosen ones and bestows bounty on his favored.  The jealous (Satan and Grendel) feel slighted by the King's favoritism and rebel by establishing from which to attack heaven.  Both Satan and Grendel are tormented by the joy that sounds from heaven and the mead-hall.

Later, Grendel will meet his doom there, giving life and reputation to Beowulf, the future King of his own people.  Then, as time weakens the once-mighty thane Beowulf will leave Heorot's protected walls and, by seeking fortune greedily, die away from its communal home.